[llvm-commits] [llvm] r130485 - in /llvm/trunk: lib/Transforms/InstCombine/InstCombineShifts.cpp test/Transforms/InstCombine/shift.ll

[Benjamin Kramer]

Author: d0k
Date: Fri Apr 29 03:15:41 2011
New Revision: 130485

URL: http://llvm.org/viewvc/llvm-project?rev=130485&view=rev
Log:
InstCombine: turn (C1 << A) << C2) into (C1 << C2) << A)

Fixes PR9809.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
    llvm/trunk/test/Transforms/InstCombine/shift.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp?rev=130485&r1=130484&r2=130485&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineShifts.cpp Fri Apr 29 03:15:41 2011
@@ -644,7 +644,14 @@
       return &I;
     }
   }
-  
+
+  // (C1 << A) << C2) -> (C1 << C2) << A)
+  Constant *C1, *C2;
+  Value *A;
+  if (match(I.getOperand(0), m_OneUse(m_Shl(m_Constant(C1), m_Value(A)))) &&
+      match(I.getOperand(1), m_Constant(C2)))
+    return BinaryOperator::CreateShl(ConstantExpr::getShl(C1, C2), A);
+
   return 0;    
 }
 

Modified: llvm/trunk/test/Transforms/InstCombine/shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/shift.ll?rev=130485&r1=130484&r2=130485&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/shift.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/shift.ll Fri Apr 29 03:15:41 2011
@@ -485,3 +485,24 @@
 ; CHECK: ret i8 %tmp551
   ret i8 %tmp55
 }
+
+; PR9809
+define i32 @test40(i32 %a, i32 %b) nounwind {
+  %shl1 = shl i32 1, %b
+  %shl2 = shl i32 %shl1, 2
+  %div = udiv i32 %a, %shl2
+  ret i32 %div
+; CHECK: @test40
+; CHECK-NEXT: add i32 %b, 2
+; CHECK-NEXT: lshr i32 %a
+; CHECK-NEXT: ret i32
+}
+
+define i32 @test41(i32 %a, i32 %b) nounwind {
+  %1 = shl i32 1, %b
+  %2 = shl i32 %1, 3
+  ret i32 %2
+; CHECK: @test41
+; CHECK-NEXT: shl i32 8, %b
+; CHECK-NEXT: ret i32
+}