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llvm-mirror/test/CodeGen/ARM/2013-05-13-AAPCS-byval-padding.ll
Stepan Dyatkovskiy adb91e7ed9 PR15868 fix.
Introduction:
In case when stack alignment is 8 and GPRs parameter part size is not N*8:
we add padding to GPRs part, so part's last byte must be recovered at
address K*8-1.
We need to do it, since remained (stack) part of parameter starts from
address K*8, and we need to "attach" "GPRs head" without gaps to it:

Stack:
|---- 8 bytes block ----| |---- 8 bytes block ----| |---- 8 bytes...
[ [padding] [GPRs head] ] [ ------ Tail passed via stack  ------ ...

FIX:
Note, once we added padding we need to correct *all* Arg offsets that are going
after padded one. That's why we need this fix: Arg offsets were never corrected
before this patch. See new test-cases included in patch.

We also don't need to insert padding for byval parameters that are stored in GPRs
only. We need pad only last byval parameter and only in case it outsides GPRs
and stack alignment = 8.
Though, stack area, allocated for recovered byval params, must satisfy
"Size mod 8 = 0" restriction.

This patch reduces stack usage for some cases:
We can reduce ArgRegsSaveArea since inner N*4 bytes sized byval params my be
"packed" with alignment 4 in some cases.

llvm-svn: 182237
2013-05-20 08:01:34 +00:00

32 lines
769 B
LLVM

;PR15293: ARM codegen ice - expected larger existing stack allocation
;RUN: llc -mtriple=arm-linux-gnueabihf < %s | FileCheck %s
%struct.S227 = type { [49 x i32], i32 }
define void @check227(
i32 %b,
%struct.S227* byval nocapture %arg0,
%struct.S227* %arg1) {
; b --> R0
; arg0 --> [R1, R2, R3, SP+0 .. SP+188)
; arg1 --> SP+188
entry:
;CHECK: sub sp, sp, #16
;CHECK: push {r11, lr}
;CHECK: add r0, sp, #12
;CHECK: stm r0, {r1, r2, r3}
;CHECK: ldr r0, [sp, #212]
;CHECK: bl useInt
;CHECK: pop {r11, lr}
;CHECK: add sp, sp, #16
%0 = ptrtoint %struct.S227* %arg1 to i32
tail call void @useInt(i32 %0)
ret void
}
declare void @useInt(i32)