[llvm] r181937 - X86: Remove redundant test instructions

Manman Ren mren at apple.com
Thu May 16 12:03:12 PDT 2013


This is related to PR16031.

Please take a look,
Thanks,
Manman

On May 15, 2013, at 3:45 PM, Pete Cooper wrote:

> Hi David
> 
> This test is breaking a buildbot.  Could you please take a look?
> 
> http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-nobootstrap-RAincremental/builds/1779
> 
> Thanks,
> Pete
> On May 15, 2013, at 3:03 PM, David Majnemer <david.majnemer at gmail.com> wrote:
> 
>> Author: majnemer
>> Date: Wed May 15 17:03:08 2013
>> New Revision: 181937
>> 
>> URL: http://llvm.org/viewvc/llvm-project?rev=181937&view=rev
>> Log:
>> X86: Remove redundant test instructions
>> 
>> Increase the number of instructions LLVM recognizes as setting the ZF
>> flag. This allows us to remove test instructions that redundantly
>> recalculate the flag.
>> 
>> Added:
>>    llvm/trunk/test/CodeGen/X86/peep-test-4.ll
>> Modified:
>>    llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
>> 
>> Modified: llvm/trunk/lib/Target/X86/X86InstrInfo.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrInfo.cpp?rev=181937&r1=181936&r2=181937&view=diff
>> ==============================================================================
>> --- llvm/trunk/lib/Target/X86/X86InstrInfo.cpp (original)
>> +++ llvm/trunk/lib/Target/X86/X86InstrInfo.cpp Wed May 15 17:03:08 2013
>> @@ -3200,8 +3200,37 @@ inline static bool isDefConvertible(Mach
>>   case X86::OR8ri:     case X86::OR64rr:   case X86::OR32rr:
>>   case X86::OR16rr:    case X86::OR8rr:    case X86::OR64rm:
>>   case X86::OR32rm:    case X86::OR16rm:   case X86::OR8rm:
>> +  case X86::NEG8r:     case X86::NEG16r:   case X86::NEG32r: case X86::NEG64r:
>> +  case X86::SAR8r1:    case X86::SAR16r1:  case X86::SAR32r1:case X86::SAR64r1:
>> +  case X86::SHR8r1:    case X86::SHR16r1:  case X86::SHR32r1:case X86::SHR64r1:
>> +  case X86::SHL8r1:    case X86::SHL16r1:  case X86::SHL32r1:case X86::SHL64r1:
>> +  case X86::ADC32ri:   case X86::ADC32ri8:
>> +  case X86::ADC32rr:   case X86::ADC64ri32:
>> +  case X86::ADC64ri8:  case X86::ADC64rr:
>> +  case X86::SBB32ri:   case X86::SBB32ri8:
>> +  case X86::SBB32rr:   case X86::SBB64ri32:
>> +  case X86::SBB64ri8:  case X86::SBB64rr:
>>   case X86::ANDN32rr:  case X86::ANDN32rm:
>>   case X86::ANDN64rr:  case X86::ANDN64rm:
>> +  case X86::BEXTR32rr: case X86::BEXTR64rr:
>> +  case X86::BEXTR32rm: case X86::BEXTR64rm:
>> +  case X86::BLSI32rr:  case X86::BLSI32rm:
>> +  case X86::BLSI64rr:  case X86::BLSI64rm:
>> +  case X86::BLSMSK32rr:case X86::BLSMSK32rm:
>> +  case X86::BLSMSK64rr:case X86::BLSMSK64rm:
>> +  case X86::BLSR32rr:  case X86::BLSR32rm:
>> +  case X86::BLSR64rr:  case X86::BLSR64rm:
>> +  case X86::BZHI32rr:  case X86::BZHI32rm:
>> +  case X86::BZHI64rr:  case X86::BZHI64rm:
>> +  case X86::LZCNT16rr: case X86::LZCNT16rm:
>> +  case X86::LZCNT32rr: case X86::LZCNT32rm:
>> +  case X86::LZCNT64rr: case X86::LZCNT64rm:
>> +  case X86::POPCNT16rr:case X86::POPCNT16rm:
>> +  case X86::POPCNT32rr:case X86::POPCNT32rm:
>> +  case X86::POPCNT64rr:case X86::POPCNT64rm:
>> +  case X86::TZCNT16rr: case X86::TZCNT16rm:
>> +  case X86::TZCNT32rr: case X86::TZCNT32rm:
>> +  case X86::TZCNT64rr: case X86::TZCNT64rm:
>>     return true;
>>   }
>> }
>> @@ -3427,13 +3456,16 @@ optimizeCompareInstr(MachineInstr *CmpIn
>>   }
>> 
>>   // Make sure Sub instruction defines EFLAGS and mark the def live.
>> -  unsigned LastOperand = Sub->getNumOperands() - 1;
>> -  assert(Sub->getNumOperands() >= 2 &&
>> -         Sub->getOperand(LastOperand).isReg() &&
>> -         Sub->getOperand(LastOperand).getReg() == X86::EFLAGS &&
>> -         "EFLAGS should be the last operand of SUB, ADD, OR, XOR, AND");
>> -  Sub->getOperand(LastOperand).setIsDef(true);
>> -  Sub->getOperand(LastOperand).setIsDead(false);
>> +  unsigned i = 0, e = Sub->getNumOperands();
>> +  for (; i != e; ++i) {
>> +    MachineOperand &MO = Sub->getOperand(i);
>> +    if (MO.isReg() && MO.isDef() && MO.getReg() == X86::EFLAGS) {
>> +      MO.setIsDead(false);
>> +      break;
>> +    }
>> +  }
>> +  assert(i != e && "Unable to locate a def EFLAGS operand");
>> +
>>   CmpInstr->eraseFromParent();
>> 
>>   // Modify the condition code of instructions in OpsToUpdate.
>> 
>> Added: llvm/trunk/test/CodeGen/X86/peep-test-4.ll
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/peep-test-4.ll?rev=181937&view=auto
>> ==============================================================================
>> --- llvm/trunk/test/CodeGen/X86/peep-test-4.ll (added)
>> +++ llvm/trunk/test/CodeGen/X86/peep-test-4.ll Wed May 15 17:03:08 2013
>> @@ -0,0 +1,154 @@
>> +; RUN: llc < %s -march=x86-64 -mattr=+bmi,+bmi2,+popcnt | FileCheck %s
>> +declare void @foo(i32)
>> +
>> +; CHECK: neg:
>> +; CHECK: negl %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +define void @neg(i32 %x) nounwind {
>> +  %sub = sub i32 0, %x
>> +  %cmp = icmp eq i32 %sub, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %sub)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: sar:
>> +; CHECK: sarl %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +define void @sar(i32 %x) nounwind {
>> +  %ashr = ashr i32 %x, 1
>> +  %cmp = icmp eq i32 %ashr, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %ashr)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: shr:
>> +; CHECK: shrl %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +define void @shr(i32 %x) nounwind {
>> +  %ashr = lshr i32 %x, 1
>> +  %cmp = icmp eq i32 %ashr, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %ashr)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: shl:
>> +; CHECK: addl %edi, %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +define void @shl(i32 %x) nounwind {
>> +  %shl = shl i32 %x, 1
>> +  %cmp = icmp eq i32 %shl, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %shl)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: adc:
>> +; CHECK: movabsq $-9223372036854775808, %rax
>> +; CHECK-NEXT: addq  %rdi, %rax
>> +; CHECK-NEXT: adcq  $0, %rsi
>> +; CHECK-NEXT: sete  %al
>> +; CHECK-NEXT: ret
>> +define zeroext i1 @adc(i128 %x) nounwind {
>> +  %add = add i128 %x, 9223372036854775808
>> +  %cmp = icmp ult i128 %add, 18446744073709551616
>> +  ret i1 %cmp
>> +}
>> +
>> +; CHECK: sbb:
>> +; CHECK: cmpq  %rdx, %rdi
>> +; CHECK-NEXT: sbbq  %rcx, %rsi
>> +; CHECK-NEXT: setns %al
>> +; CHECK-NEXT: ret
>> +define zeroext i1 @sbb(i128 %x, i128 %y) nounwind {
>> +  %sub = sub i128 %x, %y
>> +  %cmp = icmp sge i128 %sub, 0
>> +  ret i1 %cmp
>> +}
>> +
>> +; CHECK: andn:
>> +; CHECK: andnl   %esi, %edi, %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +define void @andn(i32 %x, i32 %y) nounwind {
>> +  %not = xor i32 %x, -1
>> +  %andn = and i32 %y, %not
>> +  %cmp = icmp eq i32 %andn, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %andn)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: bextr:
>> +; CHECK: bextrl   %esi, %edi, %edi
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +declare i32 @llvm.x86.bmi.bextr.32(i32, i32) nounwind readnone
>> +define void @bextr(i32 %x, i32 %y) nounwind {
>> +  %bextr = tail call i32 @llvm.x86.bmi.bextr.32(i32 %x, i32 %y)
>> +  %cmp = icmp eq i32 %bextr, 0
>> +  br i1 %cmp, label %return, label %bb
>> +
>> +bb:
>> +  tail call void @foo(i32 %bextr)
>> +  br label %return
>> +
>> +return:
>> +  ret void
>> +}
>> +
>> +; CHECK: popcnt:
>> +; CHECK: popcntl
>> +; CHECK-NEXT: je
>> +; CHECK: jmp foo
>> +; CHECK: ret
>> +declare i32 @llvm.ctpop.i32(i32) nounwind readnone
>> +define void @popcnt(i32 %x) nounwind {
>> +  %popcnt = tail call i32 @llvm.ctpop.i32(i32 %x)
>> +  %cmp = icmp eq i32 %popcnt, 0
>> +  br i1 %cmp, label %return, label %bb
>> +;
>> +bb:
>> +  tail call void @foo(i32 %popcnt)
>> +  br label %return
>> +;
>> +return:
>> +  ret void
>> +}
>> 
>> 
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