llvm-6502/pr14562.ll at 5c97450df748819381daa4c4d400c39b0d7378ae - llvm-6502 - Applefritter: Git

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Paul Redmond 5c97450df7 PR14562 - Truncation of left shift became undef

DAGCombiner::ReduceLoadWidth was converting (trunc i32 (shl i64 v, 32))
into (shl i32 v, 32) into undef. To prevent this, check the shift count
against the final result size.

Patch by: Kevin Schoedel
Reviewed by: Nadav Rotem


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174972 91177308-0d34-0410-b5e6-96231b3b80d8

2013-02-12 15:21:21 +00:00

16 lines

331 B

LLVM

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 ; RUN: llc < %s -march=x86 | FileCheck %s
 @temp1 = global i64 -77129852189294865, align 8
 define void @foo() nounwind {
   %x = load i64* @temp1, align 8
   %s = shl i64 %x, 32
   %t = trunc i64 %s to i32
   %z = zext i32 %t to i64
   store i64 %z, i64* @temp1, align 8
 ; CHECK: movl $0, temp1+4
 ; CHECK: movl $0, temp1
   ret void
 }