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Use 16 byte stack alignment for NaCl on ARM NaCl's ARM ABI uses 16 byte stack alignment, so set that in ARMSubtarget.cpp. Using 16 byte alignment exposes an issue in code generation in which a varargs function leaves a 4 byte gap between the values of r1-r3 saved to the stack and the following arguments that were passed on the stack. (Previously, this code only needed to support 4 byte and 8 byte alignment.) With this issue, llc generated: varargs_func: sub sp, sp, #16 push {lr} sub sp, sp, #12 add r0, sp, #16 // Should be 20 stm r0, {r1, r2, r3} ldr r0, .LCPI0_0 // Address of va_list add r1, sp, #16 str r1, [r0] bl external_func Fix the bug by checking for "Align > 4". Also simplify the code by using OffsetToAlignment(), and update comments. Differential Revision: http://llvm-reviews.chandlerc.com/D2677 llvm-svn: 201497
2014-02-17 02:59:48 +08:00
; RUN: llc < %s -mtriple=arm-nacl-gnueabi | FileCheck %s
declare void @llvm.va_start(i8*)
declare void @external_func(i8*)
@va_list = external global i8*
; On ARM, varargs arguments are passed in r0-r3 with the rest on the
; stack. A varargs function must therefore spill rN-r3 just below the
; function's initial stack pointer.
;
; This test checks for a bug in which a gap was left between the spill
; area and varargs arguments on the stack when using 16 byte stack
; alignment.
define void @varargs_func(i32 %arg1, ...) {
call void @llvm.va_start(i8* bitcast (i8** @va_list to i8*))
call void @external_func(i8* bitcast (i8** @va_list to i8*))
ret void
}
; CHECK-LABEL: varargs_func:
; Reserve space for the varargs save area. This currently reserves
; more than enough (16 bytes rather than the 12 bytes needed).
ARM: simplify and extend byval handling The main issue being fixed here is that APCS targets handling a "byval align N" parameter with N > 4 were miscounting what objects were where on the stack, leading to FrameLowering setting the frame pointer incorrectly and clobbering the stack. But byval handling had grown over many years, and had multiple layers of cruft trying to compensate for each other and calculate padding correctly. This only really needs to be done once, in the HandleByVal function. Elsewhere should just do what it's told by that call. I also stripped out unnecessary APCS/AAPCS distinctions (now that Clang emits byvals with the correct C ABI alignment), which simplified HandleByVal. rdar://20095672 llvm-svn: 231959
2015-03-12 02:54:22 +08:00
; CHECK: sub sp, sp, #12
ARM: try to add extra CS-register whenever stack alignment >= 8. We currently try to push an even number of registers to preserve 8-byte alignment during a function's prologue, but only when the stack alignment is prcisely 8. Many of the reasons for doing it apply also when that alignment > 8 (the extra store is often free, and can save another stack adjustment, though less frequently for 16-byte stack alignment). llvm-svn: 221321
2014-11-05 08:27:20 +08:00
; CHECK: push {r11, lr}
Use 16 byte stack alignment for NaCl on ARM NaCl's ARM ABI uses 16 byte stack alignment, so set that in ARMSubtarget.cpp. Using 16 byte alignment exposes an issue in code generation in which a varargs function leaves a 4 byte gap between the values of r1-r3 saved to the stack and the following arguments that were passed on the stack. (Previously, this code only needed to support 4 byte and 8 byte alignment.) With this issue, llc generated: varargs_func: sub sp, sp, #16 push {lr} sub sp, sp, #12 add r0, sp, #16 // Should be 20 stm r0, {r1, r2, r3} ldr r0, .LCPI0_0 // Address of va_list add r1, sp, #16 str r1, [r0] bl external_func Fix the bug by checking for "Align > 4". Also simplify the code by using OffsetToAlignment(), and update comments. Differential Revision: http://llvm-reviews.chandlerc.com/D2677 llvm-svn: 201497
2014-02-17 02:59:48 +08:00
; Align the stack pointer to a multiple of 16.
ARM: simplify and extend byval handling The main issue being fixed here is that APCS targets handling a "byval align N" parameter with N > 4 were miscounting what objects were where on the stack, leading to FrameLowering setting the frame pointer incorrectly and clobbering the stack. But byval handling had grown over many years, and had multiple layers of cruft trying to compensate for each other and calculate padding correctly. This only really needs to be done once, in the HandleByVal function. Elsewhere should just do what it's told by that call. I also stripped out unnecessary APCS/AAPCS distinctions (now that Clang emits byvals with the correct C ABI alignment), which simplified HandleByVal. rdar://20095672 llvm-svn: 231959
2015-03-12 02:54:22 +08:00
; CHECK: sub sp, sp, #12
Use 16 byte stack alignment for NaCl on ARM NaCl's ARM ABI uses 16 byte stack alignment, so set that in ARMSubtarget.cpp. Using 16 byte alignment exposes an issue in code generation in which a varargs function leaves a 4 byte gap between the values of r1-r3 saved to the stack and the following arguments that were passed on the stack. (Previously, this code only needed to support 4 byte and 8 byte alignment.) With this issue, llc generated: varargs_func: sub sp, sp, #16 push {lr} sub sp, sp, #12 add r0, sp, #16 // Should be 20 stm r0, {r1, r2, r3} ldr r0, .LCPI0_0 // Address of va_list add r1, sp, #16 str r1, [r0] bl external_func Fix the bug by checking for "Align > 4". Also simplify the code by using OffsetToAlignment(), and update comments. Differential Revision: http://llvm-reviews.chandlerc.com/D2677 llvm-svn: 201497
2014-02-17 02:59:48 +08:00
; Calculate the address of the varargs save area and save varargs
; arguments into it.
; CHECK-NEXT: add r0, sp, #20
; CHECK-NEXT: stm r0, {r1, r2, r3}