[LLVMdev] Disabling certain optimizations in llvm-gcc and llc

[Harel Cain]

Hi all,

I'm trying to prevent two things from happening:

1. Intrinsic memcpy calls of for example 16 bytes in the IR code being
translated into movl commands in x86 assembly code, for example, this code:
        call void @llvm.memcpy.p0i8.p0i8.i32(i8* %3, i8* getelementptr
inbounds ([16 x i8]* @.str1, i32 0, i32 0), i32 16, i32 1, i1 false)
translated into this x86 assembly
        movl    $6384738, 12(%ecx)      # imm = 0x616C62
        movl    $543452274, 8(%ecx)     # imm = 0x20646C72
        movl    $1870078063, 4(%ecx)    # imm = 0x6F77206F
        movl    $1819043176, (%ecx)     # imm = 0x6C6C6568
this happens even if I run llc -O0. Any way to prevent it, instead calling
memcpy in the assembly listing?

2. sizeof's being resolved to literals already at the llvm-gcc front end
stage when emitting IR, no matter if I use -O0 flag Is there any way to
prevent it?



Thanks a lot in advance!

Harel Cain
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