Disable expensive two-address optimizations at -O0. rdar://10453055

llvm-svn: 144806

llvm/lib/CodeGen/TwoAddressInstructionPass.cpp

@@ -68,6 +68,7 @@ namespace {
     MachineRegisterInfo *MRI;
     LiveVariables *LV;
     AliasAnalysis *AA;
+    CodeGenOpt::Level OptLevel;
 
     // DistanceMap - Keep track the distance of a MI from the start of the
     // current basic block.
@@ -571,6 +572,9 @@ bool
 TwoAddressInstructionPass::isProfitableToCommute(unsigned regB, unsigned regC,
                                        MachineInstr *MI, MachineBasicBlock *MBB,
                                        unsigned Dist) {
+  if (OptLevel == CodeGenOpt::None)
+    return false;
+
   // Determine if it's profitable to commute this two address instruction. In
   // general, we want no uses between this instruction and the definition of
   // the two-address register.
@@ -1193,6 +1197,9 @@ TryInstructionTransform(MachineBasicBlock::iterator &mi,
                         MachineFunction::iterator &mbbi,
                         unsigned SrcIdx, unsigned DstIdx, unsigned Dist,
                         SmallPtrSet<MachineInstr*, 8> &Processed) {
+  if (OptLevel == CodeGenOpt::None)
+    return false;
+
   MachineInstr &MI = *mi;
   const MCInstrDesc &MCID = MI.getDesc();
   unsigned regA = MI.getOperand(DstIdx).getReg();
@@ -1388,6 +1395,7 @@ bool TwoAddressInstructionPass::runOnMachineFunction(MachineFunction &MF) {
   InstrItins = TM.getInstrItineraryData();
   LV = getAnalysisIfAvailable<LiveVariables>();
   AA = &getAnalysis<AliasAnalysis>();
+  OptLevel = TM.getOptLevel();
 
   bool MadeChange = false;
 

llvm/test/CodeGen/X86/fast-isel-gep.ll

@@ -82,9 +82,8 @@ define i64 @test5(i8* %A, i32 %I, i64 %B) nounwind {
   ret i64 %v11
 ; X64: test5:
 ; X64: movslq	%e[[A1]], %rax
-; X64-NEXT: movq	(%r[[A0]],%rax), %rax
-; X64-NEXT: addq	%{{rdx|r8}}, %rax
-; X64-NEXT: ret
+; X64-NEXT: (%r[[A0]],%rax),
+; X64: ret
 }
 
 ; PR9500, rdar://9156159 - Don't do non-local address mode folding,

llvm/test/CodeGen/X86/fast-isel-x86-64.ll

@@ -82,7 +82,7 @@ entry:
   ret i64 %mul
 
 ; CHECK: test6:
-; CHECK: leaq	(,%rdi,8), %rax
+; CHECK: shlq	$3, %rdi
 }
 
 define i32 @test7(i32 %x) nounwind ssp {
@@ -90,7 +90,7 @@ entry:
   %mul = mul nsw i32 %x, 8
   ret i32 %mul
 ; CHECK: test7:
-; CHECK: leal	(,%rdi,8), %eax
+; CHECK: shll	$3, %edi
 }