Re: [llvm-commits] [llvm] r45605 - in /llvm/trunk/lib/Target/X86: X86ATTAsmPrinter.cpp X86CodeEmitter.cpp X86ISelDAGToDAG.cpp X86InstrInfo.td X86MachineFunctionInfo.h

[Chris Lattner]

On Jan 4, 2008, at 4:41 PM, Evan Cheng wrote:
> Author: evancheng
> Date: Fri Jan  4 18:41:47 2008
> New Revision: 45605
>
> URL: http://llvm.org/viewvc/llvm-project?rev=45605&view=rev
> Log:
> Combine MovePCtoStack + POP32r into one instruction MOVPC32r so it  
> can be moved if needed.

Nice evan!  With this, sinking is now able to compile code like this:

int G;
int test(int X, int Y) {
   if (X)
     return G+Y;
   return 0;
}

into:

_test:
        cmpl    $0, 4(%esp)
        je      LBB2_2  # UnifiedReturnBlock
LBB2_1: # cond_true
        call    "L2$pb"
"L2$pb":
        popl    %ecx
        movl    8(%esp), %eax
        movl    L_G$non_lazy_ptr-"L2$pb"(%ecx), %ecx
        addl    (%ecx), %eax
        ret
LBB2_2: # UnifiedReturnBlock
        xorl    %eax, %eax
        ret

instead of:

_test:
        call    "L2$pb"
"L2$pb":
        popl    %ecx
        cmpl    $0, 4(%esp)
        movl    8(%esp), %eax
        je      LBB2_2  # UnifiedReturnBlock
LBB2_1: # cond_true
        movl    L_G$non_lazy_ptr-"L2$pb"(%ecx), %ecx
        addl    (%ecx), %eax
        ret
LBB2_2: # UnifiedReturnBlock
        xorl    %eax, %eax
        ret


-Chris
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