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Support dynamic linking #244

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f61cc5a
Support dynamic linking
DrXiao May 13, 2025
8a22ab9
Fix Arm calling convention by push/pop operations
DrXiao Sep 9, 2025
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17 changes: 13 additions & 4 deletions Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,15 @@ STAGE0 := shecc
STAGE1 := shecc-stage1.elf
STAGE2 := shecc-stage2.elf

BUILTIN_LIBC ?= c.c
STAGE0_FLAGS ?= --dump-ir
STAGE1_FLAGS ?=
ifeq ($(DYNLINK),1)
BUILTIN_LIBC := c.h
STAGE0_FLAGS += --dynlink
STAGE1_FLAGS += --dynlink
endif

OUT ?= out
ARCHS = arm riscv
ARCH ?= $(firstword $(ARCHS))
Expand Down Expand Up @@ -122,9 +131,9 @@ $(OUT)/norm-lf: tools/norm-lf.c
$(VECHO) " CC+LD\t$@\n"
$(Q)$(CC) $(CFLAGS) -o $@ $^

$(OUT)/libc.inc: $(OUT)/inliner $(OUT)/norm-lf $(LIBDIR)/c.c
$(OUT)/libc.inc: $(OUT)/inliner $(OUT)/norm-lf $(LIBDIR)/$(BUILTIN_LIBC)
$(VECHO) " GEN\t$@\n"
$(Q)$(OUT)/norm-lf $(LIBDIR)/c.c $(OUT)/c.normalized.c
$(Q)$(OUT)/norm-lf $(LIBDIR)/$(BUILTIN_LIBC) $(OUT)/c.normalized.c
$(Q)$(OUT)/inliner $(OUT)/c.normalized.c $@
$(Q)$(RM) $(OUT)/c.normalized.c

Expand All @@ -143,12 +152,12 @@ $(OUT)/$(STAGE0)-sanitizer: $(OUT)/libc.inc $(OBJS)
$(OUT)/$(STAGE1): $(OUT)/$(STAGE0)
$(Q)$(STAGE1_CHECK_CMD)
$(VECHO) " SHECC\t$@\n"
$(Q)$(OUT)/$(STAGE0) --dump-ir -o $@ $(SRCDIR)/main.c > $(OUT)/shecc-stage1.log
$(Q)$(OUT)/$(STAGE0) $(STAGE0_FLAGS) -o $@ $(SRCDIR)/main.c > $(OUT)/shecc-stage1.log
$(Q)chmod a+x $@

$(OUT)/$(STAGE2): $(OUT)/$(STAGE1)
$(VECHO) " SHECC\t$@\n"
$(Q)$(TARGET_EXEC) $(OUT)/$(STAGE1) -o $@ $(SRCDIR)/main.c
$(Q)$(TARGET_EXEC) $(OUT)/$(STAGE1) $(STAGE1_FLAGS) -o $@ $(SRCDIR)/main.c

bootstrap: $(OUT)/$(STAGE2)
$(Q)chmod 775 $(OUT)/$(STAGE2)
Expand Down
47 changes: 47 additions & 0 deletions lib/c.h
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Original file line number Diff line number Diff line change
@@ -0,0 +1,47 @@
/*
* shecc - Self-Hosting and Educational C Compiler.
*
* shecc is freely redistributable under the BSD 2 clause license. See the
* file "LICENSE" for information on usage and redistribution of this file.
*/

#pragma once
/* Declarations of C standard library functions */

#define NULL 0

#define bool _Bool
#define true 1
#define false 0

/* File I/O */
typedef int FILE;
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Defines FILE as int, which is ABI-incompatible with libc's opaque FILE type and will break dynamic linking with real stdio functions.

(Based on your team's feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)

Prompt for AI agents 
Address the following comment on lib/c.h at line 18:

<comment>Defines FILE as int, which is ABI-incompatible with libc&#39;s opaque FILE type and will break dynamic linking with real stdio functions.

(Based on your team&#39;s feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)</comment>

<file context>
@@ -0,0 +1,47 @@
+#define false 0
+
+/* File I/O */
+typedef int FILE;
+FILE *fopen(char *filename, char *mode);
+int fclose(FILE *stream);
</file context>

FILE *fopen(char *filename, char *mode);
int fclose(FILE *stream);
int fgetc(FILE *stream);
char *fgets(char *str, int n, FILE *stream);
int fputc(int c, FILE *stream);

/* string-related functions */
int strlen(char *str);
int strcmp(char *s1, char *s2);
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Add const to strcmp parameters for correctness and compatibility with libc.

Prompt for AI agents 
Address the following comment on lib/c.h at line 27:

<comment>Add const to strcmp parameters for correctness and compatibility with libc.</comment>

<file context>
@@ -0,0 +1,47 @@
+
+/* string-related functions */
+int strlen(char *str);
+int strcmp(char *s1, char *s2);
+int strncmp(char *s1, char *s2, int len);
+char *strcpy(char *dest, char *src);
</file context>
Suggested change
int strcmp(char *s1, char *s2);
int strcmp(const char *s1, const char *s2);
Fix with Cubic

int strncmp(char *s1, char *s2, int len);
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Nonstandard strncmp signature (missing const, len should be size_t) is incompatible with libc and may mis-handle large sizes.

(Based on your team's feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)

Prompt for AI agents 
Address the following comment on lib/c.h at line 28:

<comment>Nonstandard strncmp signature (missing const, len should be size_t) is incompatible with libc and may mis-handle large sizes.

(Based on your team&#39;s feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)</comment>

<file context>
@@ -0,0 +1,47 @@
+/* string-related functions */
+int strlen(char *str);
+int strcmp(char *s1, char *s2);
+int strncmp(char *s1, char *s2, int len);
+char *strcpy(char *dest, char *src);
+char *strncpy(char *dest, char *src, int len);
</file context>

char *strcpy(char *dest, char *src);
char *strncpy(char *dest, char *src, int len);
char *memcpy(char *dest, char *src, int count);
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Nonstandard memcpy signature (return type and parameter types incorrect) is incompatible with libc and risks ABI mismatch.

(Based on your team's feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)

Prompt for AI agents 
Address the following comment on lib/c.h at line 31:

<comment>Nonstandard memcpy signature (return type and parameter types incorrect) is incompatible with libc and risks ABI mismatch.

(Based on your team&#39;s feedback about fixing potential issues and refining c.c/c.h for dynamic linking.)</comment>

<file context>
@@ -0,0 +1,47 @@
+int strncmp(char *s1, char *s2, int len);
+char *strcpy(char *dest, char *src);
+char *strncpy(char *dest, char *src, int len);
+char *memcpy(char *dest, char *src, int count);
+int memcmp(void *s1, void *s2, int n);
+void *memset(void *s, int c, int n);
</file context>

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memcpy should use void* for pointers, const on src, and size_t for count to match libc and avoid size truncation.

Prompt for AI agents 
Address the following comment on lib/c.h at line 31:

<comment>memcpy should use void* for pointers, const on src, and size_t for count to match libc and avoid size truncation.</comment>

<file context>
@@ -0,0 +1,47 @@
+int strncmp(char *s1, char *s2, int len);
+char *strcpy(char *dest, char *src);
+char *strncpy(char *dest, char *src, int len);
+char *memcpy(char *dest, char *src, int count);
+int memcmp(void *s1, void *s2, int n);
+void *memset(void *s, int c, int n);
</file context>
Fix with Cubic

int memcmp(void *s1, void *s2, int n);
void *memset(void *s, int c, int n);

/* formatted output string */
int printf(char *str, ...);
int sprintf(char *buffer, char *str, ...);
int snprintf(char *buffer, int n, char *str, ...);

/* Terminating program */
void exit(int exit_code);
void abort(void);

/* Dynamic memory allocation/deallocation functions */
void *malloc(int size);
void *calloc(int n, int size);
void free(void *ptr);
6 changes: 6 additions & 0 deletions mk/arm.mk
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Expand Up @@ -6,4 +6,10 @@ ARCH_DEFS = \
\#define ARCH_PREDEFINED \"__arm__\" /* defined by GNU C and RealView */\n$\
\#define ELF_MACHINE 0x28 /* up to ARMv7/Aarch32 */\n$\
\#define ELF_FLAGS 0x5000200\n$\
\#define DYN_LINKER \"/lib/ld-linux.so.3\"\n$\
\#define LIBC_SO \"libc.so.6\"\n$\
\#define PLT_FIXUP_SIZE 20\n$\
\#define PLT_ENT_SIZE 12\n$\
\#define R_ARCH_JUMP_SLOT 0x16\n$\
"
RUNNER_LD_PREFIX=-L /usr/arm-linux-gnueabi/
3 changes: 3 additions & 0 deletions mk/common.mk
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Expand Up @@ -36,6 +36,9 @@ ifneq ($(HOST_ARCH),$(ARCH_NAME))

# Generate the path to the architecture-specific qemu
TARGET_EXEC = $(shell which $(ARCH_RUNNER))
ifeq ($(DYNLINK),1)
TARGET_EXEC += $(RUNNER_LD_PREFIX)
endif
endif
export TARGET_EXEC

Expand Down
8 changes: 8 additions & 0 deletions mk/riscv.mk
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Expand Up @@ -7,4 +7,12 @@ ARCH_DEFS = \
\#define ARCH_PREDEFINED \"__riscv\" /* Older versions of the GCC toolchain defined __riscv__ */\n$\
\#define ELF_MACHINE 0xf3\n$\
\#define ELF_FLAGS 0\n$\
\#define DYN_LINKER \"/lib/ld-linux.so.3\"\n$\
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DYN_LINKER points to the ARM loader path (ld-linux.so.3), which is incorrect for RISC-V and will break dynlinked execution. Use the proper RISC-V ELF interpreter path instead.

(Based on your team's feedback about implementing RISC-V dynamic linking, this misconfiguration blocks the RISC-V dynlink workflow.)

Prompt for AI agents 
Address the following comment on mk/riscv.mk at line 10:

<comment>DYN_LINKER points to the ARM loader path (ld-linux.so.3), which is incorrect for RISC-V and will break dynlinked execution. Use the proper RISC-V ELF interpreter path instead.

(Based on your team&#39;s feedback about implementing RISC-V dynamic linking, this misconfiguration blocks the RISC-V dynlink workflow.)</comment>

<file context>
@@ -7,4 +7,12 @@ ARCH_DEFS = \
     \#define ARCH_PREDEFINED \&quot;__riscv\&quot; /* Older versions of the GCC toolchain defined __riscv__ */\n$\
     \#define ELF_MACHINE 0xf3\n$\
     \#define ELF_FLAGS 0\n$\
+    \#define DYN_LINKER \&quot;/lib/ld-linux.so.3\&quot;\n$\
+    \#define LIBC_SO \&quot;libc.so.6\&quot;\n$\
+    \#define PLT_FIXUP_SIZE 20\n$\
</file context>

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DYN_LINKER points to ARM’s /lib/ld-linux.so.3; set this to the correct RISC-V dynamic loader path to avoid invalid interpreter in produced executables.

Prompt for AI agents 
Address the following comment on mk/riscv.mk at line 10:

<comment>DYN_LINKER points to ARM’s /lib/ld-linux.so.3; set this to the correct RISC-V dynamic loader path to avoid invalid interpreter in produced executables.</comment>

<file context>
@@ -7,4 +7,12 @@ ARCH_DEFS = \
     \#define ARCH_PREDEFINED \&quot;__riscv\&quot; /* Older versions of the GCC toolchain defined __riscv__ */\n$\
     \#define ELF_MACHINE 0xf3\n$\
     \#define ELF_FLAGS 0\n$\
+    \#define DYN_LINKER \&quot;/lib/ld-linux.so.3\&quot;\n$\
+    \#define LIBC_SO \&quot;libc.so.6\&quot;\n$\
+    \#define PLT_FIXUP_SIZE 20\n$\
</file context>
Fix with Cubic

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Dynamic linker path is for ARM; RISC-V uses an arch-specific ld-linux-riscv32-*.so.1. Use the correct RISC-V interpreter path or make it configurable.

Prompt for AI agents 
Address the following comment on mk/riscv.mk at line 10:

<comment>Dynamic linker path is for ARM; RISC-V uses an arch-specific ld-linux-riscv32-*.so.1. Use the correct RISC-V interpreter path or make it configurable.</comment>

<file context>
@@ -7,4 +7,12 @@ ARCH_DEFS = \
     \#define ARCH_PREDEFINED \&quot;__riscv\&quot; /* Older versions of the GCC toolchain defined __riscv__ */\n$\
     \#define ELF_MACHINE 0xf3\n$\
     \#define ELF_FLAGS 0\n$\
+    \#define DYN_LINKER \&quot;/lib/ld-linux.so.3\&quot;\n$\
+    \#define LIBC_SO \&quot;libc.so.6\&quot;\n$\
+    \#define PLT_FIXUP_SIZE 20\n$\
</file context>
Fix with Cubic

\#define LIBC_SO \"libc.so.6\"\n$\
\#define PLT_FIXUP_SIZE 20\n$\
\#define PLT_ENT_SIZE 12\n$\
\#define R_ARCH_JUMP_SLOT 0x5\n$\
"

# TODO: Set this variable for RISC-V architecture
RUNNER_LD_PREFIX=
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RUNNER_LD_PREFIX is empty, so qemu-riscv32 won’t be given a sysroot (-L ...) for dynlinked runs, likely causing loader/lib resolution failures.

(Based on your team's feedback about making the dynamically linked shecc run, this empty setting prevents executing dynlinked RISC-V binaries.)

Prompt for AI agents 
Address the following comment on mk/riscv.mk at line 18:

<comment>RUNNER_LD_PREFIX is empty, so qemu-riscv32 won’t be given a sysroot (-L ...) for dynlinked runs, likely causing loader/lib resolution failures.

(Based on your team&#39;s feedback about making the dynamically linked shecc run, this empty setting prevents executing dynlinked RISC-V binaries.)</comment>

<file context>
@@ -7,4 +7,12 @@ ARCH_DEFS = \
     &quot;
+
+# TODO: Set this variable for RISC-V architecture
+RUNNER_LD_PREFIX=
</file context>

153 changes: 117 additions & 36 deletions src/arm-codegen.c
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Expand Up @@ -69,6 +69,8 @@ void update_elf_offset(ph2_ir_t *ph2_ir)
return;
case OP_read:
case OP_write:
case OP_push:
case OP_pop:
case OP_jump:
case OP_call:
case OP_load_func:
Expand Down Expand Up @@ -136,10 +138,17 @@ void update_elf_offset(ph2_ir_t *ph2_ir)

void cfg_flatten(void)
{
func_t *func = find_func("__syscall");
func->bbs->elf_offset = 48; /* offset of start + branch + exit in codegen */
func_t *func;

if (dynlink)
elf_offset = 80; /* offset of __libc_start_main + start in codegen */
else {
func = find_func("__syscall");
func->bbs->elf_offset = 48; /* offset of start + exit in codegen */
elf_offset =
84; /* offset of start + branch + exit + syscall in codegen */
}

elf_offset = 84; /* offset of start + branch + exit + syscall in codegen */
GLOBAL_FUNC->bbs->elf_offset = elf_offset;

for (ph2_ir_t *ph2_ir = GLOBAL_FUNC->bbs->ph2_ir_list.head; ph2_ir;
Expand All @@ -148,7 +157,10 @@ void cfg_flatten(void)
}

/* prepare 'argc' and 'argv', then proceed to 'main' function */
elf_offset += 32; /* 6 insns for main call + 2 for exit */
if (dynlink)
elf_offset += 20;
else
elf_offset += 32; /* 6 insns for main call + 2 for exit */

for (func = FUNC_LIST.head; func; func = func->next) {
/* Skip function declarations without bodies */
Expand Down Expand Up @@ -274,6 +286,12 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
else
abort();
return;
case OP_push:
emit(__stmdb(__AL, 1, __sp, rn));
return;
case OP_pop:
emit(__add_i(__AL, __sp, __sp, rn * 4));
return;
case OP_branch:
emit(__teq(rn));
if (ph2_ir->is_branch_detached) {
Expand All @@ -287,7 +305,12 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
return;
case OP_call:
func = find_func(ph2_ir->func_name);
emit(__bl(__AL, func->bbs->elf_offset - elf_code->size));
if (func->bbs)
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Potential null dereference of func; check func for NULL before accessing bbs to handle unresolved/external symbols safely.

Prompt for AI agents 
Address the following comment on src/arm-codegen.c at line 299:

<comment>Potential null dereference of func; check func for NULL before accessing bbs to handle unresolved/external symbols safely.</comment>

<file context>
@@ -282,15 +296,23 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
     case OP_call:
         func = find_func(ph2_ir-&gt;func_name);
-        emit(__bl(__AL, func-&gt;bbs-&gt;elf_offset - elf_code-&gt;size));
+        if (func-&gt;bbs)
+            ofs = func-&gt;bbs-&gt;elf_offset - elf_code-&gt;size;
+        else
</file context>
Fix with Cubic

ofs = func->bbs->elf_offset - elf_code->size;
else
ofs = (elf_plt_start + func->plt_offset) -
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Calls to external functions unconditionally use PLT when func body is missing; this should be gated by dynlink to avoid referencing non-existent PLT in static builds.

Prompt for AI agents 
Address the following comment on src/arm-codegen.c at line 303:

<comment>Calls to external functions unconditionally use PLT when func body is missing; this should be gated by dynlink to avoid referencing non-existent PLT in static builds.</comment>

<file context>
@@ -287,7 +297,12 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
+        if (func-&gt;bbs)
+            ofs = func-&gt;bbs-&gt;elf_offset - elf_code-&gt;size;
+        else
+            ofs = (elf_plt_start + func-&gt;plt_offset) -
+                  (elf_code_start + elf_code-&gt;size);
+        emit(__bl(__AL, ofs));
</file context>
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TODO:

if (func->bbs)
    ofs = func->bbs->elf_offset - elf_code->size;
else if (dynlink)
    ofs = (elf_plt_start + func->plt_offset) -
          (elf_code_start + elf_code->size);
else
    fatal("The function is not implemented");

(elf_code_start + elf_code->size);
emit(__bl(__AL, ofs));
return;
case OP_load_data_address:
emit(__movw(__AL, rd, ph2_ir->src0 + elf_data_start));
Expand All @@ -299,7 +322,10 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
return;
case OP_address_of_func:
func = find_func(ph2_ir->func_name);
ofs = elf_code_start + func->bbs->elf_offset;
if (func->bbs)
ofs = elf_code_start + func->bbs->elf_offset;
else
ofs = elf_plt_start + func->plt_offset;
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Taking address of external function unconditionally uses PLT when func body is missing; guard with dynlink to prevent invalid addresses in static builds.

Prompt for AI agents 
Address the following comment on src/arm-codegen.c at line 320:

<comment>Taking address of external function unconditionally uses PLT when func body is missing; guard with dynlink to prevent invalid addresses in static builds.</comment>

<file context>
@@ -299,7 +314,10 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
+        if (func-&gt;bbs)
+            ofs = elf_code_start + func-&gt;bbs-&gt;elf_offset;
+        else
+            ofs = elf_plt_start + func-&gt;plt_offset;
         emit(__movw(__AL, __r8, ofs));
         emit(__movt(__AL, __r8, ofs));
</file context>
Fix with Cubic

emit(__movw(__AL, __r8, ofs));
emit(__movt(__AL, __r8, ofs));
emit(__sw(__AL, __r8, rn, 0));
Expand Down Expand Up @@ -456,39 +482,72 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
}
}

void plt_generate(void);
void code_generate(void)
{
elf_data_start = elf_code_start + elf_offset;
elf_rodata_start = elf_data_start + elf_data->size;
elf_bss_start = elf_rodata_start + elf_rodata->size;
if (dynlink) {
plt_generate();
/* Call __libc_start_main() */
emit(__mov_i(__AL, __r11, 0));
emit(__mov_i(__AL, __lr, 0));
emit(__pop_word(__AL, __r1));
emit(__mov_r(__AL, __r2, __sp));
emit(__push_reg(__AL, __r2));
emit(__push_reg(__AL, __r0));
emit(__mov_i(__AL, __r12, 0));
emit(__push_reg(__AL, __r12));

int main_wrapper_offset = elf_code->size + 24;
emit(__movw(__AL, __r0, elf_code_start + main_wrapper_offset));
emit(__movt(__AL, __r0, elf_code_start + main_wrapper_offset));
emit(__mov_i(__AL, __r3, 0));
emit(__bl(__AL, (elf_plt_start + PLT_FIXUP_SIZE) -
(elf_code_start + elf_code->size)));
/* Goto the 'exit' code snippet if __libc_start_main returns */
emit(__mov_i(__AL, __r0, 127));
emit(__bl(__AL, 28));
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Hard-coded branch to an 'exit' snippet is emitted in dynlink path, but the exit snippet is only generated for static linking, leading to an invalid/incorrect branch target.

Prompt for AI agents 
Address the following comment on src/arm-codegen.c at line 500:

<comment>Hard-coded branch to an &#39;exit&#39; snippet is emitted in dynlink path, but the exit snippet is only generated for static linking, leading to an invalid/incorrect branch target.</comment>

<file context>
@@ -456,13 +474,42 @@ void emit_ph2_ir(ph2_ir_t *ph2_ir)
+                            (elf_code_start + elf_code-&gt;size)));
+        /* Goto the &#39;exit&#39; code snippet if __libc_start_main returns */
+        emit(__mov_i(__AL, __r0, 127));
+        emit(__bl(__AL, 28));
 
-    /* start */
</file context>
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These instructions are wrong. I will fix them.


/* start */
/* If the compiled program is dynamic linking, the starting
* point of 'start' is located here.
*
* Preserve 'argc' and 'argv' for the 'main' function.
* */
emit(__mov_r(__AL, __r9, __r0));
emit(__mov_r(__AL, __r10, __r1));
}
/* For both static and dynamic linking, we need to set up the stack
* and call the main function.
* */
emit(__movw(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__movt(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__sub_r(__AL, __sp, __sp, __r8));
emit(__mov_r(__AL, __r12, __sp));
emit(__bl(__AL, GLOBAL_FUNC->bbs->elf_offset - elf_code->size));
/* After global init, jump to main preparation */
emit(__b(__AL, 56)); /* PC+8: skip exit (24) + syscall (36) + ret (4) - 8 */

/* exit */
emit(__movw(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__movt(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__add_r(__AL, __sp, __sp, __r8));
emit(__mov_r(__AL, __r0, __r0));
emit(__mov_i(__AL, __r7, 1));
emit(__svc());

/* syscall */
emit(__mov_r(__AL, __r7, __r0));
emit(__mov_r(__AL, __r0, __r1));
emit(__mov_r(__AL, __r1, __r2));
emit(__mov_r(__AL, __r2, __r3));
emit(__mov_r(__AL, __r3, __r4));
emit(__mov_r(__AL, __r4, __r5));
emit(__mov_r(__AL, __r5, __r6));
emit(__svc());
emit(__bx(__AL, __lr));
if (!dynlink) {
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@cubic-dev-ai cubic-dev-ai bot Sep 8, 2025 •
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Unconditional branch still skips 56 bytes even when the exit/syscall block is omitted for dynlink, likely causing control-flow to jump into the wrong place. Make the branch size conditional (or omit it) when dynlink is enabled.

Prompt for AI agents 
Address the following comment on src/arm-codegen.c at line 521:

<comment>Unconditional branch still skips 56 bytes even when the exit/syscall block is omitted for dynlink, likely causing control-flow to jump into the wrong place. Make the branch size conditional (or omit it) when dynlink is enabled.</comment>

<file context>
@@ -471,24 +518,26 @@ void code_generate(void)
-    emit(__mov_r(__AL, __r0, __r0));
-    emit(__mov_i(__AL, __r7, 1));
-    emit(__svc());
+    if (!dynlink) {
+        /* exit - only for static linking */
+        emit(__movw(__AL, __r8, GLOBAL_FUNC-&gt;stack_size));
</file context>

emit(__bl(__AL, GLOBAL_FUNC->bbs->elf_offset - elf_code->size));
/* After global init, jump to main preparation */
emit(__b(__AL,
56)); /* PC+8: skip exit (24) + syscall (36) + ret (4) - 8 */

/* exit - only for static linking */
emit(__movw(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__movt(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__add_r(__AL, __sp, __sp, __r8));
emit(__mov_r(__AL, __r0, __r0));
emit(__mov_i(__AL, __r7, 1));
emit(__svc());

/* syscall */
emit(__mov_r(__AL, __r7, __r0));
emit(__mov_r(__AL, __r0, __r1));
emit(__mov_r(__AL, __r1, __r2));
emit(__mov_r(__AL, __r2, __r3));
emit(__mov_r(__AL, __r3, __r4));
emit(__mov_r(__AL, __r4, __r5));
emit(__mov_r(__AL, __r5, __r6));
emit(__svc());
emit(__bx(__AL, __lr));
}

ph2_ir_t *ph2_ir;
for (ph2_ir = GLOBAL_FUNC->bbs->ph2_ir_list.head; ph2_ir;
Expand All @@ -497,11 +556,16 @@ void code_generate(void)

/* prepare 'argc' and 'argv', then proceed to 'main' function */
if (MAIN_BB) {
emit(__movw(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__movt(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__add_r(__AL, __r8, __r12, __r8));
emit(__lw(__AL, __r0, __r8, 0));
emit(__add_i(__AL, __r1, __r8, 4));
if (dynlink) {
emit(__mov_r(__AL, __r0, __r9));
emit(__mov_r(__AL, __r1, __r10));
} else {
emit(__movw(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__movt(__AL, __r8, GLOBAL_FUNC->stack_size));
emit(__add_r(__AL, __r8, __r12, __r8));
emit(__lw(__AL, __r0, __r8, 0));
emit(__add_i(__AL, __r1, __r8, 4));
}
emit(__bl(__AL, MAIN_BB->elf_offset - elf_code->size));

/* exit with main's return value - r0 already has the return value */
Expand All @@ -514,3 +578,20 @@ void code_generate(void)
emit_ph2_ir(ph2_ir);
}
}

void plt_generate(void)
{
int addr_of_got = elf_got_start + PTR_SIZE * 2;
int end = plt_size - PLT_FIXUP_SIZE;
elf_write_int(elf_plt, __push_reg(__AL, __lr));
elf_write_int(elf_plt, __movw(__AL, __r10, addr_of_got));
elf_write_int(elf_plt, __movt(__AL, __r10, addr_of_got));
elf_write_int(elf_plt, __mov_r(__AL, __lr, __r10));
elf_write_int(elf_plt, __lw(__AL, __pc, __lr, 0));
for (int i = 0; i * PLT_ENT_SIZE < end; i++) {
addr_of_got = elf_got_start + PTR_SIZE * (i + 3);
elf_write_int(elf_plt, __movw(__AL, __r12, addr_of_got));
elf_write_int(elf_plt, __movt(__AL, __r12, addr_of_got));
elf_write_int(elf_plt, __lw(__AL, __pc, __r12, 0));
}
}
10 changes: 10 additions & 0 deletions src/arm.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -312,6 +312,16 @@ int __ldm(arm_cond_t cond, int w, arm_reg rn, int reg_list)
return arm_encode(cond, arm_ldm + (0x2 << 6) + (w << 1), rn, 0, reg_list);
}

int __push_reg(arm_cond_t cond, arm_reg rt)
{
return arm_encode(cond, (0x5 << 4) | 0x2, 0xd, rt, 0x4);
}

int __pop_word(arm_cond_t cond, arm_reg rt)
{
return arm_encode(cond, (0x4 << 4) | 0x9, 0xd, rt, 0x4);
}

int __b(arm_cond_t cond, int ofs)
{
int o = (ofs - 8) >> 2;
Expand Down
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