[llvm-commits] [llvm] r91378 - in /llvm/trunk: lib/CodeGen/SelectionDAG/DAGCombiner.cpp test/CodeGen/X86/setcc.ll test/CodeGen/X86/zext-shl.ll

[Evan Cheng]

On Dec 14, 2009, at 10:05 PM, Nick Lewycky wrote:

> Evan Cheng wrote:
>> Author: evancheng
>> Date: Mon Dec 14 18:41:36 2009
>> New Revision: 91378
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=91378&view=rev
>> Log:
>> Propagate zest through logical shift.
> 
> Evan, should instcombine be doing this?

I am not sure. This is one of those transforms that can go into either pass. Now that dag combine does it, I am not sure if there is benefit to adding it to instcombine.

Evan

> 
>> 
>> Added:
>>     llvm/trunk/test/CodeGen/X86/setcc.ll
>>     llvm/trunk/test/CodeGen/X86/zext-shl.ll
>> Modified:
>>     llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>> 
>> Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=91378&r1=91377&r2=91378&view=diff
>> 
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Dec 14 18:41:36 2009
>> @@ -3278,6 +3278,16 @@
>>      if (SCC.getNode()) return SCC;
>>    }
>> 
>> +  // (zext (shl (zext x), y)) ->  (shl (zext x), (zext y))
>> +  if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL)&&
>> +      N0.getOperand(0).getOpcode() == ISD::ZERO_EXTEND&&
>> +      N0.hasOneUse()) {
>> +    DebugLoc dl = N->getDebugLoc();
>> +    return DAG.getNode(N0.getOpcode(), dl, VT,
>> +                       DAG.getNode(ISD::ZERO_EXTEND, dl, VT, N0.getOperand(0)),
>> +                       DAG.getNode(ISD::ZERO_EXTEND, dl, VT, N0.getOperand(1)));
>> +  }
>> +
>>    return SDValue();
>>  }
>> 
>> 
>> Added: llvm/trunk/test/CodeGen/X86/setcc.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/setcc.ll?rev=91378&view=auto
>> 
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/setcc.ll (added)
>> +++ llvm/trunk/test/CodeGen/X86/setcc.ll Mon Dec 14 18:41:36 2009
>> @@ -0,0 +1,13 @@
>> +; RUN: llc<  %s -mtriple=x86_64-apple-darwin | FileCheck %s
>> +
>> +define zeroext i16 @t1(i16 zeroext %x) nounwind readnone ssp {
>> +entry:
>> +; CHECK: t1:
>> +; CHECK: seta %al
>> +; CHECK: movzbl %al, %eax
>> +; CHECK: shll $5, %eax
>> +  %0 = icmp ugt i16 %x, 26                        ;<i1>  [#uses=1]
>> +  %iftmp.1.0 = select i1 %0, i16 32, i16 0        ;<i16>  [#uses=1]
>> +  ret i16 %iftmp.1.0
>> +}
>> +
>> 
>> Added: llvm/trunk/test/CodeGen/X86/zext-shl.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/zext-shl.ll?rev=91378&view=auto
>> 
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/zext-shl.ll (added)
>> +++ llvm/trunk/test/CodeGen/X86/zext-shl.ll Mon Dec 14 18:41:36 2009
>> @@ -0,0 +1,38 @@
>> +; RUN: llc<  %s -march=x86 | FileCheck %s
>> +
>> +define i32 @t1(i8 zeroext %x) nounwind readnone ssp {
>> +entry:
>> +; CHECK: t1:
>> +; CHECK: shll
>> +; CHECK-NOT: movzwl
>> +; CHECK: ret
>> +  %0 = zext i8 %x to i16
>> +  %1 = shl i16 %0, 5
>> +  %2 = zext i16 %1 to i32
>> +  ret i32 %2
>> +}
>> +
>> +define i32 @t2(i8 zeroext %x) nounwind readnone ssp {
>> +entry:
>> +; CHECK: t2:
>> +; CHECK: shrl
>> +; CHECK-NOT: movzwl
>> +; CHECK: ret
>> +  %0 = zext i8 %x to i16
>> +  %1 = lshr i16 %0, 3
>> +  %2 = zext i16 %1 to i32
>> +  ret i32 %2
>> +}
>> +
>> +define i32 @t3(i8 zeroext %x, i8 zeroext %y) nounwind readnone ssp {
>> +entry:
>> +; CHECK: t3:
>> +; CHECK: shll
>> +; CHECK-NOT: movzwl
>> +; CHECK: ret
>> +  %0 = zext i8 %x to i16
>> +  %1 = zext i8 %y to i16
>> +  %2 = shl i16 %0, %1
>> +  %3 = zext i16 %2 to i32
>> +  ret i32 %3
>> +}
>> 
>> 
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at cs.uiuc.edu
>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>> 
>