[llvm] r181937 - X86: Remove redundant test instructions

Pete Cooper peter_cooper at apple.com
Wed May 15 15:45:04 PDT 2013


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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