[CIR][CodeGen] Fix extra Yieldop case during try-catch generation

[bruteforceboy]

Currently, trying to generate CIR for the following code snippet yield.cpp fails. Using bin/clang++ yield.cpp -Xclang -fclangir -Xclang -emit-cir -S -o -:

struct S {
  S() {};
  int a;
};

void foo() {
  try {
    S s;
  } catch (...) {
    foo();
  }
}

The error:

loc("yield.cpp":6:6): error: 'cir.yield' op must be the last operation in the parent block

There is an extra YieldOp! The CIR dump before verification looks something like:

"cir.scope"() ({
  %0 = "cir.alloca"() <{alignment = 4 : i64, allocaType = !cir.struct<struct "S" {!cir.int<s, 32>} #cir.record.decl.ast>, ast = #cir.var.decl.ast, init, name = "s"}> : () -> !cir.ptr<!cir.struct<struct "S" {!cir.int<s, 32>} #cir.record.decl.ast>>
  "cir.try"() <{catch_types = [#cir.all]}> ({
    "cir.call"(%0) <{callee = @_ZN1SC1Ev, calling_conv = 1 : i32, exception, extra_attrs = #cir<extra({})>, side_effect = 1 : i32}> ({
      "cir.yield"() : () -> ()
    }) : (!cir.ptr<!cir.struct<struct "S" {!cir.int<s, 32>} #cir.record.decl.ast>>) -> ()
    "cir.yield"() : () -> ()
  }, {
    %1 = "cir.catch_param"() : () -> !cir.ptr<!cir.void>
    "cir.call"() <{ast = #cir.call.expr.ast, callee = @_Z3foov, calling_conv = 1 : i32, exception, extra_attrs = #cir<extra({})>, side_effect = 1 : i32}> ({
      "cir.yield"() : () -> ()
      "cir.yield"() : () -> () <--- **DUPLICATE**
    }) : () -> ()
    "cir.yield"() : () -> ()
  }) : () -> ()
  "cir.yield"() : () -> ()
}, {
}) : () -> ()

This PR adds a check for an already existing terminator before creating a YieldOp during the cleanup.

[bruteforceboy]

btw, in CodeGen/try-catch.cpp, these tests do not use the right prefix:

// CIR: cir.func @_Z3tc4v()
unsigned long long tc4() {
  int x = 50, y = 3;
  unsigned long long z;

  // CIR-NOT: cir.try
  try {
    int a = 4;
    a++;

    // CIR: cir.scope {
    // CIR: cir.alloca !s32i, !cir.ptr<!s32i>, ["a", init]
    // CIR-NOT: cir.alloca !cir.ptr<!cir.eh.info>
    // CIR: cir.const #cir.int<4> : !s32i
    // CIR: cir.unary(inc,
    // CIR: cir.store %11, %8 : !s32i, !cir.ptr<!s32i>
  } catch (int idx) {
    z = 98;
    idx++;
  }

  return z;
}

CIR should be CHECK, so these checks aren't being tested. I can fix these in this PR too if that is okay.

[bcardosolopes]

CIR should be CHECK, so these checks aren't being tested. I can fix these in this PR too if that is okay.

Oh no! Good catch, thanks. You can add as part of this PR if you prefer (or a separate one), I'm fine either way

[bruteforceboy]

CIR should be CHECK, so these checks aren't being tested. I can fix these in this PR too if that is okay.

Oh no! Good catch, thanks. You can add as part of this PR if you prefer (or a separate one), I'm fine either way

I've updated them)