Codegen of array initialization generates weird LLVM-IR

[orbiri]

When generating LLVM-IR through CIR for the following code:

int g = 5;
int g_arr[5] = {1, 2, 3, g};

We get the following LLVM-IR:

  store i32 1, ptr @g_arr, align 4
  store i32 2, ptr getelementptr (i32, ptr @g_arr, i64 1), align 4
  store i32 3, ptr getelementptr (i32, ptr getelementptr (i32, ptr @g_arr, i64 1), i64 1), align 4
  %2 = load i32, ptr @g, align 4
  store i32 %2, ptr getelementptr (i32, ptr getelementptr (i32, ptr getelementptr (i32, ptr @g_arr, i64 1), i64 1), i64 1), align 4

Notices the triple GEP(GEP(GEP(arr,1),1),1) for the last store. Clang generates a sane GEP(arr,3) for that in codegen.

The root cause is in the way the codegen is written in CIRGenExprAgg.cpp in AggExprEmitter::emitArrayInit.

Would be nice to get to parity here :)

[beamandala]

Hi, can I work on this issue?

[Lancern]

Hi, can I work on this issue?

@beamandala Assigning this to you.

[Rajveer100]

@orbiri
Is this fixed? Since as per my reproduction I get:

  store i32 1, ptr @g_arr, align 4
  store i32 2, ptr getelementptr inbounds (i32, ptr @g_arr, i64 1), align 4
  store i32 3, ptr getelementptr inbounds (i32, ptr @g_arr, i64 2), align 4
  %0 = load i32, ptr @g, align 4
  store i32 %0, ptr getelementptr inbounds (i32, ptr @g_arr, i64 3), align 4

Edit: Apologies, ignore my comment, I did the invocation with regular clang instead of CIR.

[beamandala]

@Lancern Can you please unassign me from this issue since @Rajveer100 has already opened a PR for this?

[Lancern]

@beamandala Unassigned.