Move ashr optimization from InstCombineShift to InstSimplify.

Refactor code, no functionality change, test case moved from instcombine to instsimplify.

Differential Revision: http://reviews.llvm.org/D4102

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213231 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index fd7a4de6903786b7ef7c44093799a1a0c57bb32c..6ac1ae8d5ed1783a66b035fcb5061f47f1c9b709 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -1346,6 +1346,11 @@ static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
       cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
     return X;
 
+  // Arithmetic shifting an all-sign-bit value is a no-op.
+  unsigned NumSignBits = ComputeNumSignBits(Op0);
+  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
+    return Op0;
+
   return nullptr;
 }
 

diff --git a/lib/Transforms/InstCombine/InstCombineShifts.cpp b/lib/Transforms/InstCombine/InstCombineShifts.cpp
index 2495747da5fe6321fce069fed8915009ccaea352..2f91c204dbd929d032a674641e52adf57b95645a 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineShifts.cpp
+++ b/lib/Transforms/InstCombine/InstCombineShifts.cpp
@@ -815,10 +815,5 @@ Instruction *InstCombiner::visitAShr(BinaryOperator &I) {
                         APInt::getSignBit(I.getType()->getScalarSizeInBits())))
     return BinaryOperator::CreateLShr(Op0, Op1);
 
-  // Arithmetic shifting an all-sign-bit value is a no-op.
-  unsigned NumSignBits = ComputeNumSignBits(Op0);
-  if (NumSignBits == Op0->getType()->getScalarSizeInBits())
-    return ReplaceInstUsesWith(I, Op0);
-
   return nullptr;
 }

diff --git a/test/Transforms/InstCombine/ashr-nop.ll b/test/Transforms/InstCombine/ashr-nop.ll
deleted file mode 100644 (file)
index 870ede3..0000000
--- a/test/Transforms/InstCombine/ashr-nop.ll
+++ /dev/null
@@ -1,8 +0,0 @@
-; RUN: opt < %s -instcombine -S | not grep ashr
-
-define i32 @foo(i32 %x) {
-  %o = and i32 %x, 1
-  %n = add i32 %o, -1
-  %t = ashr i32 %n, 17
-  ret i32 %t
-}

diff --git a/test/Transforms/InstSimplify/ashr-nop.ll b/test/Transforms/InstSimplify/ashr-nop.ll
new file mode 100644 (file)
index 0000000..0914d72
--- /dev/null
+++ b/test/Transforms/InstSimplify/ashr-nop.ll
@@ -0,0 +1,10 @@
+; RUN: opt < %s -instsimplify -S | FileCheck %s
+
+; CHECK-LABEL: @foo
+; CHECK-NOT: ashr
+define i32 @foo(i32 %x) {
+ %o = and i32 %x, 1
+ %n = add i32 %o, -1
+ %t = ashr i32 %n, 17
+ ret i32 %t
+}