[llvm] r273897 - [InstCombine] use m_APInt for div --> ashr fold

[Sanjay Patel via llvm-commits]

Author: spatel
Date: Mon Jun 27 12:25:57 2016
New Revision: 273897

URL: http://llvm.org/viewvc/llvm-project?rev=273897&view=rev
Log:
[InstCombine] use m_APInt for div --> ashr fold
The APInt matcher works with splat vectors, so we get this fold for vectors too.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
    llvm/trunk/test/Transforms/InstCombine/exact.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp?rev=273897&r1=273896&r2=273897&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Mon Jun 27 12:25:57 2016
@@ -1143,14 +1143,12 @@ Instruction *InstCombiner::visitSDiv(Bin
   if (match(Op1, m_AllOnes()))
     return BinaryOperator::CreateNeg(Op0);
 
-  if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
-    // sdiv X, C  -->  ashr exact X, log2(C)
-    if (I.isExact() && RHS->getValue().isNonNegative() &&
-        RHS->getValue().isPowerOf2()) {
-      Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
-                                            RHS->getValue().exactLogBase2());
-      return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
-    }
+  // sdiv exact X, C  -->  ashr exact X, log2(C)
+  const APInt *Op1C;
+  if (match(Op1, m_APInt(Op1C)) && I.isExact() && Op1C->isNonNegative() &&
+      Op1C->isPowerOf2()) {
+    Value *ShAmt = ConstantInt::get(Op1->getType(), Op1C->exactLogBase2());
+    return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
   }
 
   if (Constant *RHS = dyn_cast<Constant>(Op1)) {

Modified: llvm/trunk/test/Transforms/InstCombine/exact.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/exact.ll?rev=273897&r1=273896&r2=273897&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/exact.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/exact.ll Mon Jun 27 12:25:57 2016
@@ -19,6 +19,15 @@ define i32 @sdiv2(i32 %x) {
   ret i32 %y
 }
 
+define <2 x i32> @sdiv2_vec(<2 x i32> %x) {
+; CHECK-LABEL: @sdiv2_vec(
+; CHECK-NEXT:    [[Y:%.*]] = ashr exact <2 x i32> %x, <i32 7, i32 7>
+; CHECK-NEXT:    ret <2 x i32> [[Y]]
+;
+  %y = sdiv exact <2 x i32> %x, <i32 128, i32 128>
+  ret <2 x i32> %y
+}
+
 define i32 @sdiv3(i32 %x) {
 ; CHECK-LABEL: @sdiv3(
 ; CHECK-NEXT:    [[Y:%.*]] = srem i32 %x, 3