From 3139ff8f7b5e3eeb170d77ac8472fc4ca596ec0e Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Thu, 11 Sep 2008 22:47:57 +0000
Subject: [PATCH] Fix a vectorshuffle instcombine bug introduced by r55995.
 Patch by Nicolas Capens!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@56129 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../Scalar/InstructionCombining.cpp           |  5 ++-
 .../InstCombine/{pr2645.ll => pr2645-0.ll}    |  0
 test/Transforms/InstCombine/pr2645-1.ll       | 39 +++++++++++++++++++
 3 files changed, 43 insertions(+), 1 deletion(-)
 rename test/Transforms/InstCombine/{pr2645.ll => pr2645-0.ll} (100%)
 create mode 100644 test/Transforms/InstCombine/pr2645-1.ll

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 5a9d1de2e35..f02a7108fd6 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -11311,8 +11311,11 @@ Instruction *InstCombiner::visitShuffleVectorInst(ShuffleVectorInst &SVI) {
   unsigned VWidth = cast<VectorType>(SVI.getType())->getNumElements();
   uint64_t AllOnesEltMask = ~0ULL >> (64-VWidth);
   if (VWidth <= 64 &&
-      SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts))
+      SimplifyDemandedVectorElts(&SVI, AllOnesEltMask, UndefElts)) {
+    LHS = SVI.getOperand(0);
+    RHS = SVI.getOperand(1);
     MadeChange = true;
+  }
   
   // Canonicalize shuffle(x    ,x,mask) -> shuffle(x, undef,mask')
   // Canonicalize shuffle(undef,x,mask) -> shuffle(x, undef,mask').
diff --git a/test/Transforms/InstCombine/pr2645.ll b/test/Transforms/InstCombine/pr2645-0.ll
similarity index 100%
rename from test/Transforms/InstCombine/pr2645.ll
rename to test/Transforms/InstCombine/pr2645-0.ll
diff --git a/test/Transforms/InstCombine/pr2645-1.ll b/test/Transforms/InstCombine/pr2645-1.ll
new file mode 100644
index 00000000000..194d2cd18f7
--- /dev/null
+++ b/test/Transforms/InstCombine/pr2645-1.ll
@@ -0,0 +1,39 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep shufflevector
+; PR2645
+
+; instcombine shouldn't delete the shufflevector.
+
+define internal void @""(i8*, i32, i8*) {
+; <label>:3
+        br label %4
+
+; <label>:4             ; preds = %6, %3
+        %.0 = phi i32 [ 0, %3 ], [ %19, %6 ]            ; <i32> [#uses=4]
+        %5 = icmp slt i32 %.0, %1               ; <i1> [#uses=1]
+        br i1 %5, label %6, label %20
+
+; <label>:6             ; preds = %4
+        %7 = getelementptr i8* %2, i32 %.0              ; <i8*> [#uses=1]
+        %8 = bitcast i8* %7 to <4 x i16>*               ; <<4 x i16>*> [#uses=1]
+        %9 = load <4 x i16>* %8, align 1                ; <<4 x i16>> [#uses=1]
+        %10 = bitcast <4 x i16> %9 to <1 x i64>         ; <<1 x i64>> [#uses=1]
+        %11 = call <2 x i64> @foo(<1 x i64> %10)
+; <<2 x i64>> [#uses=1]
+        %12 = bitcast <2 x i64> %11 to <4 x i32>                ; <<4 x i32>> [#uses=1]
+        %13 = bitcast <4 x i32> %12 to <8 x i16>                ; <<8 x i16>> [#uses=2]
+        %14 = shufflevector <8 x i16> %13, <8 x i16> %13, <8 x i32> < i32 0, i32 0, i32 1, i32 1, i32 2, i32 2, i32 3, i32 3 >          ; <<8 x i16>> [#uses=1]
+        %15 = bitcast <8 x i16> %14 to <4 x i32>                ; <<4 x i32>> [#uses=1]
+        %16 = sitofp <4 x i32> %15 to <4 x float>               ; <<4 x float>> [#uses=1]
+        %17 = getelementptr i8* %0, i32 %.0             ; <i8*> [#uses=1]
+        %18 = bitcast i8* %17 to <4 x float>*           ; <<4 x float>*> [#uses=1]
+        store <4 x float> %16, <4 x float>* %18, align 1
+        %19 = add i32 %.0, 1            ; <i32> [#uses=1]
+        br label %4
+
+; <label>:20            ; preds = %4
+        call void @llvm.x86.mmx.emms( )
+        ret void
+}
+
+declare <2 x i64> @foo(<1 x i64>)
+declare void @llvm.x86.mmx.emms( )
-- 
2.34.1