mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-26 21:32:10 +00:00
beac75da37
Since mem2reg isn't run at -O0, we get a ton of reloads from the stack,
for example, before, this code:
int foo(int x, int y, int z) {
return x+y+z;
}
used to compile into:
_foo: ## @foo
subq $12, %rsp
movl %edi, 8(%rsp)
movl %esi, 4(%rsp)
movl %edx, (%rsp)
movl 8(%rsp), %edx
movl 4(%rsp), %esi
addl %edx, %esi
movl (%rsp), %edx
addl %esi, %edx
movl %edx, %eax
addq $12, %rsp
ret
Now we produce:
_foo: ## @foo
subq $12, %rsp
movl %edi, 8(%rsp)
movl %esi, 4(%rsp)
movl %edx, (%rsp)
movl 8(%rsp), %edx
addl 4(%rsp), %edx ## Folded load
addl (%rsp), %edx ## Folded load
movl %edx, %eax
addq $12, %rsp
ret
Fewer instructions and less register use = faster compiles.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113102 91177308-0d34-0410-b5e6-96231b3b80d8
35 lines
822 B
LLVM
35 lines
822 B
LLVM
; RUN: llc < %s -fast-isel -mtriple=i386-apple-darwin | FileCheck %s
|
|
|
|
@src = external global i32
|
|
|
|
; rdar://6653118
|
|
define i32 @loadgv() nounwind {
|
|
entry:
|
|
%0 = load i32* @src, align 4
|
|
%1 = load i32* @src, align 4
|
|
%2 = add i32 %0, %1
|
|
store i32 %2, i32* @src
|
|
ret i32 %2
|
|
; This should fold one of the loads into the add.
|
|
; CHECK: loadgv:
|
|
; CHECK: movl L_src$non_lazy_ptr, %ecx
|
|
; CHECK: movl (%ecx), %eax
|
|
; CHECK: addl (%ecx), %eax
|
|
; CHECK: movl %eax, (%ecx)
|
|
; CHECK: ret
|
|
|
|
}
|
|
|
|
%stuff = type { i32 (...)** }
|
|
@LotsStuff = external constant [4 x i32 (...)*]
|
|
|
|
define void @t(%stuff* %this) nounwind {
|
|
entry:
|
|
store i32 (...)** getelementptr ([4 x i32 (...)*]* @LotsStuff, i32 0, i32 2), i32 (...)*** null, align 4
|
|
ret void
|
|
; CHECK: _t:
|
|
; CHECK: movl $0, %eax
|
|
; CHECK: movl L_LotsStuff$non_lazy_ptr, %ecx
|
|
|
|
}
|