From df303bd7f2c15d6c5fcbee951bd8c21dde3f2718 Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Sat, 5 Jan 2008 09:18:04 +0000 Subject: [PATCH] Chris and Evan noticed that this check was compleatly fubared. I was checking that there was a from a global instead of a load from the stub for a global, which is the one that's safe to hoist. Consider this program: volatile char G[100]; int B(char *F, int N) { for (; N > 0; --N) F[N] = G[N]; } In static mode, we shouldn't be hoisting the load from G: $ llc -relocation-model=static -o - a.bc -march=x86 -machine-licm LBB1_1: # bb.preheader leal -1(%eax), %edx testl %edx, %edx movl $1, %edx cmovns %eax, %edx xorl %esi, %esi LBB1_2: # bb movb _G(%eax), %bl movb %bl, (%ecx,%eax) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45626 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86InstrInfo.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp index ede88f28ffe..9d714279684 100644 --- a/lib/Target/X86/X86InstrInfo.cpp +++ b/lib/Target/X86/X86InstrInfo.cpp @@ -171,12 +171,15 @@ bool X86InstrInfo::isReallySideEffectFree(MachineInstr *MI) const { case X86::MOV32rm: if (MI->getOperand(1).isRegister()) { unsigned Reg = MI->getOperand(1).getReg(); + const X86Subtarget &ST = TM.getSubtarget(); // Loads from global addresses which aren't redefined in the function are // side effect free. if (Reg != 0 && MRegisterInfo::isVirtualRegister(Reg) && MI->getOperand(2).isImm() && MI->getOperand(3).isReg() && - MI->getOperand(4).isGlobal() && MI->getOperand(2).getImm() == 1 && + MI->getOperand(4).isGlobal() && + ST.GVRequiresExtraLoad(MI->getOperand(4).getGlobal(), TM, false) && + MI->getOperand(2).getImm() == 1 && MI->getOperand(3).getReg() == 0) return true; }