[llvm-commits] [llvm] r158946 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineMulDivRem.cpp test/Transforms/InstCombine/div-shift.ll test/Transforms/InstCombine/sdiv-shift.ll

[Evan Cheng]

Author: evancheng
Date: Thu Jun 21 17:52:49 2012
New Revision: 158946

URL: http://llvm.org/viewvc/llvm-project?rev=158946&view=rev
Log:
Look pass zext to strength reduce an udiv. Patch by David Majnemer. rdar://11721329

Added:
    llvm/trunk/test/Transforms/InstCombine/div-shift.ll
Removed:
    llvm/trunk/test/Transforms/InstCombine/sdiv-shift.ll
Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp?rev=158946&r1=158945&r2=158946&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp Thu Jun 21 17:52:49 2012
@@ -464,9 +464,12 @@
 
   // X udiv (C1 << N), where C1 is "1<<C2"  -->  X >> (N+C2)
   { const APInt *CI; Value *N;
-    if (match(Op1, m_Shl(m_Power2(CI), m_Value(N)))) {
+    if (match(Op1, m_Shl(m_Power2(CI), m_Value(N))) ||
+        match(Op1, m_ZExt(m_Shl(m_Power2(CI), m_Value(N))))) {
       if (*CI != 1)
         N = Builder->CreateAdd(N, ConstantInt::get(I.getType(),CI->logBase2()));
+      if (ZExtInst *Z = dyn_cast<ZExtInst>(Op1))
+        N = Builder->CreateZExt(N, Z->getDestTy());
       if (I.isExact())
         return BinaryOperator::CreateExactLShr(Op0, N);
       return BinaryOperator::CreateLShr(Op0, N);

Added: llvm/trunk/test/Transforms/InstCombine/div-shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/div-shift.ll?rev=158946&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/div-shift.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/div-shift.ll Thu Jun 21 17:52:49 2012
@@ -0,0 +1,23 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+define i32 @t1(i16 zeroext %x, i32 %y) nounwind {
+entry:
+; CHECK: t1
+; CHECK-NOT: sdiv
+; CHECK: lshr i32 %conv
+  %conv = zext i16 %x to i32
+  %s = shl i32 2, %y
+  %d = sdiv i32 %conv, %s
+  ret i32 %d
+}
+
+; rdar://11721329
+define i64 @t2(i64 %x, i32 %y) nounwind  {
+; CHECK: t2
+; CHECK-NOT: udiv
+; CHECK: lshr i64 %x
+  %1 = shl i32 1, %y
+  %2 = zext i32 %1 to i64
+  %3 = udiv i64 %x, %2
+  ret i64 %3
+}

Removed: llvm/trunk/test/Transforms/InstCombine/sdiv-shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sdiv-shift.ll?rev=158945&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sdiv-shift.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sdiv-shift.ll (removed)
@@ -1,9 +0,0 @@
-; RUN: opt < %s -instcombine -S | not grep div
-
-define i32 @a(i16 zeroext %x, i32 %y) nounwind {
-entry:
-	%conv = zext i16 %x to i32
-	%s = shl i32 2, %y
-	%d = sdiv i32 %conv, %s
-	ret i32 %d
-}