Commit 801857c5 authored by Huihui Zhang's avatar Huihui Zhang
Browse files

[ConstantFold][SVE] Fix constant folding for bitcast. 

Do not iterate on scalable vector type in BitCastConstantVector.
Continuation work of D70985, D71147.

Support for folding bitcast into splat value is kept in D74095, as
it depends on D71637.

Differential Revision: https://reviews.llvm.org/D71389
parent a6258684

llvm/lib/IR/ConstantFold.cpp

+5 −0
Original line number Diff line number Diff line
@@ -47,6 +47,11 @@ static Constant *BitCastConstantVector(Constant *CV, VectorType *DstTy) { 
  if (CV->isAllOnesValue()) return Constant::getAllOnesValue(DstTy);

  if (CV->isNullValue()) return Constant::getNullValue(DstTy);



  // Do not iterate on scalable vector. The num of elements is unknown at

  // compile-time.

  if (DstTy->isScalable())

    return nullptr;



  // If this cast changes element count then we can't handle it here:

  // doing so requires endianness information.  This should be handled by

  // Analysis/ConstantFolding.cpp

llvm/test/Analysis/ConstantFolding/bitcast.ll

0 → 100644
+12 −0
Original line number Diff line number Diff line 
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py

; RUN: opt < %s -constprop -S -verify | FileCheck %s



define <vscale x 4 x float> @bitcast_scalable_constant() {

; CHECK-LABEL: @bitcast_scalable_constant(

; CHECK-NEXT:    ret <vscale x 4 x float> bitcast (<vscale x 4 x i32> shufflevector (<vscale x 4 x i32> insertelement (<vscale x 4 x i32> undef, i32 1, i32 0), <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer) to <vscale x 4 x float>)

;

  %i1 = insertelement <vscale x 4 x i32> undef, i32 1, i32 0

  %i2 = shufflevector <vscale x 4 x i32> %i1, <vscale x 4 x i32> undef, <vscale x 4 x i32> zeroinitializer

  %i3 = bitcast <vscale x 4 x i32> %i2 to <vscale x 4 x float>

  ret <vscale x 4 x float> %i3

}