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930aaa18e9
There is not an official documented ABI for frame pointers in Thumb2, but we should try to emit something which is useful. We use r7 as the frame pointer for Thumb code, which currently means that if a function needs to save a high register (r8-r11), it will get pushed to the stack between the frame pointer (r7) and link register (r14). This means that while a stack unwinder can follow the chain of frame pointers up the stack, it cannot know the offset to lr, so does not know which functions correspond to the stack frames. To fix this, we need to push the callee-saved registers in two batches, with the first push saving the low registers, fp and lr, and the second push saving the high registers. This is already implemented, but previously only used for iOS. This patch turns it on for all Thumb2 targets when frame pointers are required by the ABI, and the frame pointer is r7 (Windows uses r11, so this isn't a problem there). If frame pointer elimination is enabled we still emit a single push/pop even if we need a frame pointer for other reasons, to avoid increasing code size. We must also ensure that lr is pushed to the stack when using a frame pointer, so that we end up with a complete frame record. Situations that could cause this were rare, because we already push lr in most situations so that we can return using the pop instruction. Differential Revision: https://reviews.llvm.org/D23516 llvm-svn: 279506
66 lines
2.4 KiB
LLVM
66 lines
2.4 KiB
LLVM
; RUN: llc -verify-machineinstrs -mtriple=armv7k-apple-ios8.0 -mcpu=cortex-a7 -o - %s | FileCheck --check-prefix=CHECK --check-prefix=OPT --check-prefix=TAILCALL %s
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; RUN: llc -O0 -verify-machineinstrs -mtriple=armv7k-apple-ios8.0 -mcpu=cortex-a7 -o - %s | FileCheck %s
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; RUN: llc -verify-machineinstrs -mtriple=armv7-apple-ios -o - %s | FileCheck --check-prefix=CHECK --check-prefix=OPT %s
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; RUN: llc -O0 -verify-machineinstrs -mtriple=armv7-apple-ios -o - %s | FileCheck %s
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; Parameter with swiftself should be allocated to r10.
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; CHECK-LABEL: swiftself_param:
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; CHECK: mov r0, r10
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define i8 *@swiftself_param(i8* swiftself %addr0) "no-frame-pointer-elim"="true" {
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ret i8 *%addr0
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}
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; Check that r10 is used to pass a swiftself argument.
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; CHECK-LABEL: call_swiftself:
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; CHECK: mov r10, r0
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; CHECK: bl {{_?}}swiftself_param
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define i8 *@call_swiftself(i8* %arg) "no-frame-pointer-elim"="true" {
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%res = call i8 *@swiftself_param(i8* swiftself %arg)
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ret i8 *%res
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}
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; r10 should be saved by the callee even if used for swiftself
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; CHECK-LABEL: swiftself_clobber:
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; CHECK: push {r10}
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; ...
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; CHECK: pop {r10}
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define i8 *@swiftself_clobber(i8* swiftself %addr0) "no-frame-pointer-elim"="true" {
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call void asm sideeffect "", "~{r10}"()
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ret i8 *%addr0
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}
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; Demonstrate that we do not need any movs when calling multiple functions
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; with swiftself argument.
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; CHECK-LABEL: swiftself_passthrough:
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; OPT-NOT: mov{{.*}}r10
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; OPT: bl {{_?}}swiftself_param
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; OPT-NOT: mov{{.*}}r10
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; OPT-NEXT: bl {{_?}}swiftself_param
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define void @swiftself_passthrough(i8* swiftself %addr0) "no-frame-pointer-elim"="true" {
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call i8 *@swiftself_param(i8* swiftself %addr0)
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call i8 *@swiftself_param(i8* swiftself %addr0)
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ret void
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}
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; We can use a tail call if the callee swiftself is the same as the caller one.
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; CHECK-LABEL: swiftself_tail:
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; TAILCALL: b {{_?}}swiftself_param
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; TAILCALL-NOT: pop
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define i8* @swiftself_tail(i8* swiftself %addr0) "no-frame-pointer-elim"="true" {
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call void asm sideeffect "", "~{r10}"()
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%res = tail call i8* @swiftself_param(i8* swiftself %addr0)
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ret i8* %res
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}
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; We can not use a tail call if the callee swiftself is not the same as the
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; caller one.
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; CHECK-LABEL: swiftself_notail:
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; CHECK: mov r10, r0
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; CHECK: bl {{_?}}swiftself_param
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; CHECK: pop
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define i8* @swiftself_notail(i8* swiftself %addr0, i8* %addr1) nounwind "no-frame-pointer-elim"="true" {
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%res = tail call i8* @swiftself_param(i8* swiftself %addr1)
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ret i8* %res
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}
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