50a97aacac
Re-commit of 32e8b550e5439c7e4aafa73894faffd5f25d0d05 This patch rearranges emission of CFI instructions, so the resulting DWARF and `.eh_frame` information is precise at every instruction. The current state is that the unwind info is emitted only after the function prologue. This is fine for synchronous (e.g. C++) exceptions, but the information is generally incorrect when the program counter is at an instruction in the prologue or the epilogue, for example: ``` stp x29, x30, [sp, #-16]! // 16-byte Folded Spill mov x29, sp .cfi_def_cfa w29, 16 ... ``` after the `stp` is executed the (initial) rule for the CFA still says the CFA is in the `sp`, even though it's already offset by 16 bytes A correct unwind info could look like: ``` stp x29, x30, [sp, #-16]! // 16-byte Folded Spill .cfi_def_cfa_offset 16 mov x29, sp .cfi_def_cfa w29, 16 ... ``` Having this information precise up to an instruction is useful for sampling profilers that would like to get a stack backtrace. The end goal (towards this patch is just a step) is to have fully working `-fasynchronous-unwind-tables`. Reviewed By: danielkiss, MaskRay Differential Revision: https://reviews.llvm.org/D111411
75 lines
2.3 KiB
LLVM
75 lines
2.3 KiB
LLVM
; RUN: llc -verify-machineinstrs -mtriple=arm64-none-linux-gnu -frame-pointer=non-leaf -disable-post-ra < %s | FileCheck %s
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declare void @use_addr(i8*)
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@addr = global i8* null
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define void @test_bigframe() {
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; CHECK-LABEL: test_bigframe:
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; CHECK: .cfi_startproc
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%var1 = alloca i8, i32 20000000
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%var2 = alloca i8, i32 16
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%var3 = alloca i8, i32 20000000
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; CHECK: sub sp, sp, #4095, lsl #12 // =16773120
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; CHECK-NEXT: .cfi_def_cfa_offset 16773136
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; CHECK-NEXT: sub sp, sp, #4095, lsl #12 // =16773120
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; CHECK-NEXT: .cfi_def_cfa_offset 33546256
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; CHECK-NEXT: sub sp, sp, #1575, lsl #12 // =6451200
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; CHECK-NEXT: .cfi_def_cfa_offset 39997456
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; CHECK-NEXT: sub sp, sp, #2576
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; CHECK-NEXT: .cfi_def_cfa_offset 40000032
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; CHECK: add [[TMP:x[0-9]+]], sp, #4095, lsl #12
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; CHECK: add [[TMP1:x[0-9]+]], [[TMP]], #787, lsl #12
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; CHECK: add {{x[0-9]+}}, [[TMP1]], #3344
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store volatile i8* %var1, i8** @addr
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%var1plus2 = getelementptr i8, i8* %var1, i32 2
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store volatile i8* %var1plus2, i8** @addr
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; CHECK: add [[TMP:x[0-9]+]], sp, #4095, lsl #12
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; CHECK: add [[TMP1:x[0-9]+]], [[TMP]], #787, lsl #12
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; CHECK: add {{x[0-9]+}}, [[TMP1]], #3328
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store volatile i8* %var2, i8** @addr
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%var2plus2 = getelementptr i8, i8* %var2, i32 2
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store volatile i8* %var2plus2, i8** @addr
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store volatile i8* %var3, i8** @addr
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%var3plus2 = getelementptr i8, i8* %var3, i32 2
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store volatile i8* %var3plus2, i8** @addr
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; CHECK: add sp, sp, #4095, lsl #12
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; CHECK: add sp, sp, #4095, lsl #12
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; CHECK: add sp, sp, #1575, lsl #12
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; CHECK: add sp, sp, #2576
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; CHECK: .cfi_endproc
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ret void
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}
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define void @test_mediumframe() {
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; CHECK-LABEL: test_mediumframe:
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%var1 = alloca i8, i32 1000000
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%var2 = alloca i8, i32 16
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%var3 = alloca i8, i32 1000000
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; CHECK: sub sp, sp, #488, lsl #12 // =1998848
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; CHECK-NEXT: .cfi_def_cfa_offset 1998864
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; CHECK-NEXT: sub sp, sp, #1168
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; CHECK-NEXT: .cfi_def_cfa_offset 2000032
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store volatile i8* %var1, i8** @addr
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; CHECK: add [[VAR1ADDR:x[0-9]+]], sp, #244, lsl #12
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; CHECK: add [[VAR1ADDR]], [[VAR1ADDR]], #592
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; CHECK: add [[VAR2ADDR:x[0-9]+]], sp, #244, lsl #12
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; CHECK: add [[VAR2ADDR]], [[VAR2ADDR]], #576
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store volatile i8* %var2, i8** @addr
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; CHECK: add sp, sp, #488, lsl #12
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; CHECK: add sp, sp, #1168
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ret void
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}
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