From: Sanjay Patel <spatel@rotateright.com>
Date: Wed, 31 Aug 2016 22:18:43 +0000 (+0000)
Subject: [InstCombine] allow icmp (shr exact X, C2), C fold for splat constant vectors
X-Git-Tag: llvmorg-4.0.0-rc1~10938
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=0d70831d733f89d743ce5e4444796b834ae5797c;p=platform%2Fupstream%2Fllvm.git

[InstCombine] allow icmp (shr exact X, C2), C fold for splat constant vectors

The enhancement to foldICmpDivConstant ( http://llvm.org/viewvc/llvm-project?view=revision&revision=280299 )
allows us to remove the ConstantInt check; no other changes needed.

llvm-svn: 280300
---

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index a564771..d05b8d1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -1876,11 +1876,6 @@ Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp,
     if (IsAShr && (!Shr->isExact() || ShAmtVal == TypeBits - 1))
       return nullptr;
 
-    // FIXME: This check restricts this fold to scalar types.
-    ConstantInt *ShAmt = dyn_cast<ConstantInt>(Shr->getOperand(1));
-    if (!ShAmt)
-      return nullptr;
-
     // Revisit the shift (to delete it).
     Worklist.Add(Shr);
 
diff --git a/llvm/test/Transforms/InstCombine/exact.ll b/llvm/test/Transforms/InstCombine/exact.ll
index f93bc8e..cf10b70 100644
--- a/llvm/test/Transforms/InstCombine/exact.ll
+++ b/llvm/test/Transforms/InstCombine/exact.ll
@@ -120,11 +120,9 @@ define i1 @ashr_icmp2(i64 %X) {
   ret i1 %Z
 }
 
-; FIXME: Vectors should fold the same way.
 define <2 x i1> @ashr_icmp2_vec(<2 x i64> %X) {
 ; CHECK-LABEL: @ashr_icmp2_vec(
-; CHECK-NEXT:    [[Y:%.*]] = ashr exact <2 x i64> %X, <i64 2, i64 2>
-; CHECK-NEXT:    [[Z:%.*]] = icmp slt <2 x i64> [[Y]], <i64 4, i64 4>
+; CHECK-NEXT:    [[Z:%.*]] = icmp slt <2 x i64> %X, <i64 16, i64 16>
 ; CHECK-NEXT:    ret <2 x i1> [[Z]]
 ;
   %Y = ashr exact <2 x i64> %X, <i64 2, i64 2>