llvm-6502/fold-imm.ll at be8cc2a3dedeb7685f07e68cdc4b9502eb97eb2b - llvm-6502 - Applefritter: Git

6502/llvm-6502

mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-11-12 15:05:06 +00:00

Evan Cheng 884c70c912 On x86 favors folding short immediate into some arithmetic operations (e.g. add, and, xor, etc.) because materializing an immediate in a register is expensive in turns of code size.

e.g.
movl 4(%esp), %eax
addl $4, %eax

is 2 bytes shorter than

movl $4, %eax
addl 4(%esp), %eax


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60139 91177308-0d34-0410-b5e6-96231b3b80d8

2008-11-27 00:49:46 +00:00

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LLVM

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 ; RUN: llvm-as < %s | llc -march=x86 | grep inc
 ; RUN: llvm-as < %s | llc -march=x86 | grep add | grep 4
 define i32 @test(i32 %X) nounwind {
 entry:
 	%0 = add i32 %X, 1
 	ret i32 %0
 }
 define i32 @test2(i32 %X) nounwind {
 entry:
 	%0 = add i32 %X, 4
 	ret i32 %0
 }