[PATCH] D148803: [ConstantFolding] Fix crash when folding vector llvm.is.fpclass

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

In D148803#4286333 <https://reviews.llvm.org/D148803#4286333>, @mstorsjo wrote:

> I've bisected a failed assert to this commit. Repro:
>
>   $ cat repro.c 
>   int a;
>   float *b;
>   float c;
>   void d() {
>     float *e = d;
>     for (int f = 0; f < a; f++) {
>       c = b[f];
>       e[f] = 10.f * c;
>       if (__builtin_isnormal(e[f]))
>         e[f] = 351.f;
>     }
>   }
>   $ clang -target aarch64-linux-gnu -c repro.c -O2
>   clang: ../lib/IR/Instructions.cpp:652: void llvm::CallInst::init(llvm::FunctionType*, llvm::Value*, llvm::ArrayRef<llvm::Value*>, llvm::ArrayRef<llvm::OperandBundleDefT<llvm::Value*> >, const llvm::Twine&): Assertion `(i >= FTy->getNumParams() || FTy->getParamType(i) == Args[i]->getType()) && "Calling a function with a bad signature!"' failed.

Thanks! Here's an IR repro:

  ; RUN: opt < %s -passes=loop-vectorize -S | FileCheck %s
  
  target triple = "aarch64-unknown-linux-gnu"
  
  define void @d() {
  bb:
    br label %bb2
  
  bb1:
    ret void
  
  bb2:
    %i = phi i64 [ 0, %bb ], [ %i7, %bb2 ]
    %i3 = load float, ptr null, align 4
    %i4 = getelementptr float, ptr @d, i64 %i
    %i5 = tail call i1 @llvm.is.fpclass.f32(float 0.0, i32 0)
    %i6 = select i1 %i5, float 0.0, float 0.0
    store float %i6, ptr %i4, align 4
    %i7 = add i64 %i, 1
    %i8 = icmp eq i64 %i7, 0
    br i1 %i8, label %bb1, label %bb2
  }
  
  declare i1 @llvm.is.fpclass.f32(float, i32 immarg)

The problem is that `VPWidenCallRecipe::execute` assumes that vector intrinsics are overloaded on their result type. `llvm.is.fpclass` is overloaded on the type of its first argument instead. I'm not sure what the best fix is.


Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D148803