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Craig Topper 8b0dff8c8e [DAGCombiner] Don't fold zext_vector_inreg/sext_vector_inreg(undef) to undef. Fold to 0.
zext_vector_inreg needs to produces 0s in the extended bits and
sext_vector_inreg needs to produce upper bits that are all the
same. So we should fold them to a 0 vector instead of undef.

Fixes PR46585.
2020-07-04 11:42:53 -07:00

36 lines
1.2 KiB
LLVM

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc < %s -mtriple=x86_64-apple-macosx | FileCheck %s
@global = external local_unnamed_addr global i8
@global.1 = external local_unnamed_addr global i64
define void @spam() local_unnamed_addr {
; CHECK-LABEL: spam:
; CHECK: ## %bb.0: ## %bb
; CHECK-NEXT: xorl %eax, %eax
; CHECK-NEXT: testb %al, %al
; CHECK-NEXT: je LBB0_2
; CHECK-NEXT: ## %bb.1: ## %bb9
; CHECK-NEXT: movq _global.1@{{.*}}(%rip), %rax
; CHECK-NEXT: movq $1, (%rax)
; CHECK-NEXT: LBB0_2: ## %bb8
; CHECK-NEXT: retq
bb:
%tmp = load i8, i8* @global, align 1
%tmp1 = and i8 %tmp, 1
%tmp2 = insertelement <8 x i8> undef, i8 %tmp1, i32 0
%tmp3 = ashr <8 x i8> %tmp2, <i8 7, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0>
%tmp4 = shufflevector <8 x i8> %tmp3, <8 x i8> undef, <8 x i32> zeroinitializer
%tmp5 = icmp slt <8 x i8> %tmp4, zeroinitializer
%tmp6 = bitcast <8 x i1> %tmp5 to i8
%tmp7 = icmp eq i8 %tmp6, 0
br i1 %tmp7, label %bb8, label %bb9
bb8: ; preds = %bb9, %bb
ret void
bb9: ; preds = %bb
store i64 1, i64* @global.1, align 8
br label %bb8
}