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[DebugInfo] Make describeLoadedValue() reg aware Summary: Currently the describeLoadedValue() hook is assumed to describe the value of the instruction's first explicit define. The hook will not be called for instructions with more than one explicit define. This commit adds a register parameter to the describeLoadedValue() hook, and invokes the hook for all registers in the worklist. This will allow us to for example describe instructions which produce more than two parameters' values; e.g. Hexagon's various combine instructions. This also fixes situations in our downstream target where we may pass smaller parameters in the high part of a register. If such a parameter's value is produced by a larger copy instruction, we can't describe the call site value using the super-register, and we instead need to know which sub-register that should be used. This also allows us to handle cases like this: $ebx = [...] $rdi = MOVSX64rr32 $ebx $esi = MOV32rr $edi CALL64pcrel32 @call The hook will first be invoked for the MOV32rr instruction, which will say that @call's second parameter (passed in $esi) is described by $edi. As $edi is not preserved it will be added to the worklist. When we get to the MOVSX64rr32 instruction, we need to describe two values; the sign-extended value of $ebx -> $rdi for the first parameter, and $ebx -> $edi for the second parameter, which is now possible. This commit modifies the dbgcall-site-lea-interpretation.mir test case. In the test case, the values of some 32-bit parameters were produced with LEA64r. Perhaps we can in general cases handle such by emitting expressions that AND out the lower 32-bits, but I have not been able to land in a case where a LEA64r is used for a 32-bit parameter instead of LEA64_32 from C code. I have not found a case where it would be useful to describe parameters using implicit defines, so in this patch the hook is still only invoked for explicit defines of forwarding registers. Reviewers: djtodoro, NikolaPrica, aprantl, vsk Reviewed By: djtodoro, vsk Subscribers: ormris, hiraditya, llvm-commits Tags: #debug-info, #llvm Differential Revision: https://reviews.llvm.org/D70431
2019-12-09 17:46:16 +08:00
# RUN: llc -O1 -debug-entry-values -start-after=livedebugvalues -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
# Based on the following C reproducer:
#
# extern void call(long, int);
# extern int a, b, c, d;
#
# int e() { return a; }
#
# int main() {
# d = c;
# b = e();
# call(c, c);
# return 0;
# }
--- |
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64"
@a = external global i32, align 4
@c = external global i32, align 4
@d = external global i32, align 4
@b = external global i32, align 4
; Function Attrs: noinline norecurse nounwind readonly
define i32 @e() #0 !dbg !13 {
entry:
%0 = load i32, i32* @a, align 4, !dbg !16
ret i32 %0, !dbg !16
}
; Function Attrs: noinline nounwind
define i32 @main() #1 !dbg !17 {
entry:
%0 = load i32, i32* @c, align 4, !dbg !19
store i32 %0, i32* @d, align 4, !dbg !19
%call = tail call i32 @e(), !dbg !20
store i32 %call, i32* @b, align 4, !dbg !20
%conv = sext i32 %0 to i64, !dbg !21
tail call void @call(i64 %conv, i32 %0), !dbg !21
ret i32 0, !dbg !22
}
declare !dbg !4 void @call(i64, i32)
attributes #0 = { noinline norecurse nounwind readonly "frame-pointer"="all" }
attributes #1 = { noinline nounwind "frame-pointer"="all" }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!9, !10, !11}
!llvm.ident = !{!12}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
!1 = !DIFile(filename: "x86_two_defs.c", directory: "/")
!2 = !{}
!3 = !{!4}
!4 = !DISubprogram(name: "call", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
!5 = !DISubroutineType(types: !6)
!6 = !{null, !7, !8}
!7 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!9 = !{i32 2, !"Dwarf Version", i32 5}
!10 = !{i32 2, !"Debug Info Version", i32 3}
!11 = !{i32 1, !"wchar_size", i32 4}
!12 = !{!"clang version 10.0.0"}
!13 = distinct !DISubprogram(name: "e", scope: !1, file: !1, line: 5, type: !14, scopeLine: 5, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!14 = !DISubroutineType(types: !15)
!15 = !{!8}
!16 = !DILocation(line: 6, scope: !13)
!17 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 9, type: !14, scopeLine: 9, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
!19 = !DILocation(line: 10, scope: !17)
!20 = !DILocation(line: 11, scope: !17)
!21 = !DILocation(line: 12, scope: !17)
!22 = !DILocation(line: 13, scope: !17)
...
---
name: e
tracksRegLiveness: true
body: |
bb.0.entry:
frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
CFI_INSTRUCTION def_cfa_offset 16
CFI_INSTRUCTION offset $rbp, -16
$rbp = frame-setup MOV64rr $rsp
CFI_INSTRUCTION def_cfa_register $rbp
renamable $eax = MOV32rm $rip, 1, $noreg, @a, $noreg, debug-location !16 :: (dereferenceable load 4 from @a)
$rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !16
CFI_INSTRUCTION def_cfa $rsp, 8, debug-location !16
RETQ $eax, debug-location !16
...
---
name: main
tracksRegLiveness: true
callSites:
- { bb: 0, offset: 10 }
- { bb: 0, offset: 14, fwdArgRegs:
- { arg: 0, reg: '$rdi' }
- { arg: 1, reg: '$esi' } }
body: |
bb.0.entry:
liveins: $rbx
frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
CFI_INSTRUCTION def_cfa_offset 16
CFI_INSTRUCTION offset $rbp, -16
$rbp = frame-setup MOV64rr $rsp
CFI_INSTRUCTION def_cfa_register $rbp
frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp, debug-location !19
frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
CFI_INSTRUCTION offset $rbx, -24
renamable $ebx = MOV32rm $rip, 1, $noreg, @c, $noreg, debug-location !19 :: (dereferenceable load 4 from @c)
MOV32mr $rip, 1, $noreg, @d, $noreg, renamable $ebx, debug-location !19 :: (store 4 into @d)
CALL64pcrel32 @e, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !20
MOV32mr $rip, 1, $noreg, @b, $noreg, killed renamable $eax, debug-location !20 :: (store 4 into @b)
renamable $rdi = MOVSX64rr32 killed renamable $ebx, debug-location !21
$esi = MOV32rr $edi, debug-location !21
CALL64pcrel32 @call, csr_64, implicit $rsp, implicit $ssp, implicit $rdi, implicit killed $esi, implicit-def $rsp, implicit-def $ssp, debug-location !21
$eax = XOR32rr undef $eax, undef $eax, implicit-def dead $eflags, debug-location !22
$rsp = frame-destroy ADD64ri8 $rsp, 8, implicit-def dead $eflags, debug-location !22
$rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !22
$rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !22
CFI_INSTRUCTION def_cfa $rsp, 8, debug-location !22
RETQ $eax, debug-location !22
...
# Verify that call site entries are emitted for both parameters in the call to
# %call. Both parameters should be described by the preserved $ebx register,
# and the value for the first parameter (passed in $rdi) should be
# sign-extended to 64 bits.
# CHECK: DW_TAG_call_site_parameter
# CHECK-NEXT: DW_AT_location (DW_OP_reg4 RSI)
# CHECK-NEXT: DW_AT_call_value (DW_OP_breg3 RBX+0)
# CHECK: DW_TAG_call_site_parameter
# CHECK-NEXT: DW_AT_location (DW_OP_reg5 RDI)
# CHECK-NEXT: DW_AT_call_value (DW_OP_breg3 RBX+0, DW_OP_constu 0xffffffff, DW_OP_and, DW_OP_convert ({{.*}}) "DW_ATE_signed_32", DW_OP_convert ({{.*}}) "DW_ATE_signed_64")