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llvm-project/llvm/test/Transforms/InstCombine/pr20059.ll

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Fix for PR20059 (instcombine reorders shufflevector after instruction that may trap) In PR20059 ( http://llvm.org/pr20059 ), instcombine eliminates shuffles that are necessary before performing an operation that can trap (srem). This patch calls isSafeToSpeculativelyExecute() and bails out of the optimization in SimplifyVectorOp() if needed. Differential Revision: http://reviews.llvm.org/D4424 llvm-svn: 212629
2014-07-10 00:34:54 +08:00
; RUN: opt -S -instcombine < %s | FileCheck %s
; In PR20059 ( http://llvm.org/pr20059 ), shufflevector operations are reordered/removed
; for an srem operation. This is not a valid optimization because it may cause a trap
; on div-by-zero.
; CHECK-LABEL: @do_not_reorder
; CHECK: %splat1 = shufflevector <4 x i32> %p1, <4 x i32> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: %splat2 = shufflevector <4 x i32> %p2, <4 x i32> undef, <4 x i32> zeroinitializer
; CHECK-NEXT: %retval = srem <4 x i32> %splat1, %splat2
define <4 x i32> @do_not_reorder(<4 x i32> %p1, <4 x i32> %p2) {
%splat1 = shufflevector <4 x i32> %p1, <4 x i32> undef, <4 x i32> zeroinitializer
%splat2 = shufflevector <4 x i32> %p2, <4 x i32> undef, <4 x i32> zeroinitializer
%retval = srem <4 x i32> %splat1, %splat2
ret <4 x i32> %retval
}