diff options
| -rw-r--r-- | lib/Target/X86/X86InstrInfo.cpp | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp index 59b8116812..08ae6d374b 100644 --- a/lib/Target/X86/X86InstrInfo.cpp +++ b/lib/Target/X86/X86InstrInfo.cpp @@ -22,8 +22,15 @@ #include "llvm/CodeGen/LiveVariables.h" #include "llvm/CodeGen/SSARegMap.h" #include "llvm/Target/TargetOptions.h" +#include "llvm/Support/CommandLine.h" using namespace llvm; +namespace { + cl::opt<bool> + EnableConvert3Addr("enable-x86-conv-3-addr", + cl::desc("Enable convertToThreeAddress for X86")); +} + X86InstrInfo::X86InstrInfo(X86TargetMachine &tm) : TargetInstrInfo(X86Insts, array_lengthof(X86Insts)), TM(tm), RI(tm, *this) { @@ -144,6 +151,21 @@ bool X86InstrInfo::isReallyTriviallyReMaterializable(MachineInstr *MI) const { return true; } +/// hasLiveCondCodeDef - True if MI has a condition code def, e.g. EFLAGS, that +/// is not marked dead. +static bool hasLiveCondCodeDef(MachineInstr *MI) { + if (!EnableConvert3Addr) + return true; + for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { + MachineOperand &MO = MI->getOperand(i); + if (MO.isRegister() && MO.isDef() && + MO.getReg() == X86::EFLAGS && !MO.isDead()) { + return true; + } + } + return false; +} + /// convertToThreeAddress - This method must be implemented by targets that /// set the M_CONVERTIBLE_TO_3_ADDR flag. When this flag is set, the target /// may be able to convert a two-address instruction into a true @@ -169,7 +191,7 @@ X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI, bool DisableLEA16 = true; switch (MI->getOpcode()) { - default: return 0; + default: break; // All others need to check for live condition code defs. case X86::SHUFPSrri: { assert(MI->getNumOperands() == 4 && "Unknown shufps instruction!"); if (!TM.getSubtarget<X86Subtarget>().hasSSE2()) return 0; @@ -253,10 +275,7 @@ X86InstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI, } } - // FIXME: None of these instructions are promotable to LEAs without - // additional information. In particular, LEA doesn't set the flags that - // add and inc do. :( - if (0) + if (!hasLiveCondCodeDef(MI)) switch (MI->getOpcode()) { case X86::INC32r: case X86::INC64_32r: |