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llvm-mirror/test/DebugInfo/X86/fission-ranges.ll
Paul Robinson 1e74415545 [FastISel] Flush local value map on ever instruction 
Local values are constants or addresses that can't be folded into
the instruction that uses them. FastISel materializes these in a
"local value" area that always dominates the current insertion
point, to try to avoid materializing these values more than once
(per block).

https://reviews.llvm.org/D43093 added code to sink these local
value instructions to their first use, which has two beneficial
effects. One, it is likely to avoid some unnecessary spills and
reloads; two, it allows us to attach the debug location of the
user to the local value instruction. The latter effect can
improve the debugging experience for debuggers with a "set next
statement" feature, such as the Visual Studio debugger and PS4
debugger, because instructions to set up constants for a given
statement will be associated with the appropriate source line.

There are also some constants (primarily addresses) that could be
produced by no-op casts or GEP instructions; the main difference
from "local value" instructions is that these are values from
separate IR instructions, and therefore could have multiple users
across multiple basic blocks. D43093 avoided sinking these, even
though they were emitted to the same "local value" area as the
other instructions. The patch comment for D43093 states:

  Local values may also be used by no-op casts, which adds the
  register to the RegFixups table. Without reversing the RegFixups
  map direction, we don't have enough information to sink these
  instructions.

This patch undoes most of D43093, and instead flushes the local
value map after(*) every IR instruction, using that instruction's
debug location. This avoids sometimes incorrect locations used
previously, and emits instructions in a more natural order.

This does mean materialized values are not re-used across IR
instruction boundaries; however, only about 5% of those values
were reused in an experimental self-build of clang.

(*) Actually, just prior to the next instruction. It seems like
it would be cleaner the other way, but I was having trouble
getting that to work.

Differential Revision: https://reviews.llvm.org/D91734
2020-11-25 13:05:00 -05:00

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; RUN: llc -split-dwarf-file=foo.dwo -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
; RUN: llvm-dwarfdump -v %t | FileCheck %s
; RUN: llvm-objdump -h %t | FileCheck --check-prefix=HDR %s
; RUN: llc -dwarf-version=5 -O0 %s -mtriple=x86_64-unknown-linux-gnu -filetype=obj -o %t
; RUN: llvm-dwarfdump -v %t | FileCheck --check-prefix=V5RNGLISTS %s
; RUN: llc -O0 %s -mtriple=x86_64-unknown-linux-gnu -stop-after=livedebugvalues -o -| FileCheck --check-prefix=CHECK-MIR %s
; LiveDebugValues should produce DBG_VALUEs for variable "b" in successive
; blocks once we recognize that it is spilled.
; CHECK-MIR: ![[BDIVAR:[0-9]+]] = !DILocalVariable(name: "b"
; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 24, DW_OP_minus)
; CHECK-MIR-LABEL: bb.6.for.inc13:
; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 24, DW_OP_minus)
; CHECK-MIR-LABEL: bb.7.for.inc16:
; CHECK-MIR: DBG_VALUE $rsp, 0, ![[BDIVAR]], !DIExpression(DW_OP_constu, 24, DW_OP_minus)
; CHECK: .debug_info contents:
; CHECK: DW_TAG_compile_unit
; CHECK-NEXT: DW_AT_stmt_list
; CHECK-NEXT: DW_AT_comp_dir
; CHECK-NEXT: DW_AT_GNU_dwo_name
; CHECK-NEXT: DW_AT_GNU_dwo_id
; CHECK-NEXT: DW_AT_GNU_ranges_base
; CHECK-NEXT: DW_AT_low_pc
; CHECK-NEXT: DW_AT_high_pc
; CHECK-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset] (0x00000000)
; CHECK: .debug_info.dwo contents:
; CHECK: DW_TAG_formal_parameter
; CHECK-NEXT: DW_AT_const_value [DW_FORM_sdata] (1)
; CHECK-NEXT: DW_AT_name {{.*}} "p")
; CHECK: DW_AT_location [DW_FORM_sec_offset] ([[A:0x[0-9a-z]*]]:
; CHECK: DW_AT_location [DW_FORM_sec_offset] ([[E:0x[0-9a-z]*]]:
; CHECK: DW_AT_location [DW_FORM_sec_offset] ([[B:0x[0-9a-z]*]]:
; CHECK: DW_AT_location [DW_FORM_sec_offset] ([[D:0x[0-9a-z]*]]:
; CHECK: DW_AT_ranges [DW_FORM_sec_offset] (0x00000000
; CHECK-NOT: .debug_loc contents:
; CHECK-NOT: Beginning address offset
; CHECK: .debug_loc.dwo contents:
; Don't assume these locations are entirely correct - feel free to update them
; if they've changed due to a bugfix, change in register allocation, etc.
; CHECK: [[A]]:
; CHECK-NEXT: DW_LLE_startx_length (0x00000001, 0x00000011): DW_OP_consts +0, DW_OP_stack_value
; CHECK-NEXT: DW_LLE_startx_length (0x00000002, 0x0000000b): DW_OP_reg0 RAX
; CHECK-NEXT: DW_LLE_startx_length (0x00000003, 0x00000012): DW_OP_breg7 RSP-4
; CHECK-NEXT: DW_LLE_end_of_list ()
; CHECK: [[E]]:
; CHECK-NEXT: DW_LLE_startx_length (0x00000004, 0x0000000b): DW_OP_reg0 RAX
; CHECK-NEXT: DW_LLE_startx_length (0x00000005, 0x0000005a): DW_OP_breg7 RSP-48
; CHECK-NEXT: DW_LLE_end_of_list ()
; CHECK: [[B]]:
; CHECK-NEXT: DW_LLE_startx_length (0x00000006, 0x0000000b): DW_OP_reg0 RAX
; CHECK-NEXT: DW_LLE_startx_length (0x00000007, 0x00000042): DW_OP_breg7 RSP-24
; CHECK-NEXT: DW_LLE_end_of_list ()
; CHECK: [[D]]:
; CHECK-NEXT: DW_LLE_startx_length (0x00000008, 0x0000000b): DW_OP_reg0 RAX
; CHECK-NEXT: DW_LLE_startx_length (0x00000009, 0x0000002a): DW_OP_breg7 RSP-12
; CHECK-NEXT: DW_LLE_end_of_list ()
; Make sure we don't produce any relocations in any .dwo section (though in particular, debug_info.dwo)
; HDR-NOT: .rela.{{.*}}.dwo
; Make sure we have enough stuff in the debug_addr to cover the address indexes
; (9 is the last index in debug_loc.dwo, making 10 entries of 8 bytes each,
; 10 * 8 == 80 base 10 == 50 base 16)
; HDR: .debug_addr 00000050
; HDR-NOT: .rela.{{.*}}.dwo
; Check for the existence of a DWARF v5-style range list table in the .debug_rnglists
; section and that the compile unit has a DW_AT_rnglists_base attribute.
; The table should contain at least one rangelist with at least 2 individual ranges.
; V5RNGLISTS: .debug_info contents:
; V5RNGLISTS: DW_TAG_compile_unit
; V5RNGLISTS-NOT: DW_TAG
; V5RNGLISTS: DW_AT_rnglists_base [DW_FORM_sec_offset] (0x0000000c)
; V5RNGLISTS: .debug_rnglists contents:
; V5RNGLISTS-NEXT: 0x00000000: range list header: length = 0x00000015, format = DWARF32, version = 0x0005,
; V5RNGLISTS-SAME: addr_size = 0x08, seg_size = 0x00, offset_entry_count = 0x00000001
; V5RNGLISTS-NEXT: offsets: [
; V5RNGLISTS-NEXT: => 0x00000010
; V5RNGLISTS-NEXT: ]
; V5RNGLISTS-NEXT: ranges:
; V5RNGLISTS-NEXT: 0x00000010: [DW_RLE_offset_pair]:
; V5RNGLISTS-NEXT: 0x00000013: [DW_RLE_offset_pair]:
; V5RNGLISTS: 0x{{[0-9a-f]+}}: [DW_RLE_end_of_list]
; From the code:
; extern int c;
; static void foo (int p)
; {
; int a, b;
; unsigned int d, e;
; for (a = 0; a < 30; a++)
; for (d = 0; d < 30; d++)
; for (b = 0; b < 30; b++)
; for (e = 0; e < 30; e++)
; {
; int *w = &c;
; *w &= p;
; }
; }
; void
; bar ()
; {
; foo (1);
; }
; compiled with:
; clang -g -S -gsplit-dwarf -O1 small.c
@c = external global i32
; Function Attrs: nounwind uwtable
define void @bar() #0 !dbg !4 {
entry:
tail call fastcc void @foo(), !dbg !27
ret void, !dbg !28
}
; Function Attrs: nounwind uwtable
define internal fastcc void @foo() #0 !dbg !8 {
entry:
tail call void @llvm.dbg.value(metadata i32 1, metadata !13, metadata !DIExpression()), !dbg !30
tail call void @llvm.dbg.value(metadata i32 0, metadata !14, metadata !DIExpression()), !dbg !31
%c.promoted9 = load i32, i32* @c, align 4, !dbg !32, !tbaa !33
br label %for.cond1.preheader, !dbg !31
for.cond1.preheader: ; preds = %for.inc16, %entry
%and.lcssa.lcssa.lcssa10 = phi i32 [ %c.promoted9, %entry ], [ %and, %for.inc16 ]
%a.08 = phi i32 [ 0, %entry ], [ %inc17, %for.inc16 ]
br label %for.cond4.preheader, !dbg !37
for.cond4.preheader: ; preds = %for.inc13, %for.cond1.preheader
%and.lcssa.lcssa7 = phi i32 [ %and.lcssa.lcssa.lcssa10, %for.cond1.preheader ], [ %and, %for.inc13 ]
%d.06 = phi i32 [ 0, %for.cond1.preheader ], [ %inc14, %for.inc13 ]
br label %for.cond7.preheader, !dbg !38
for.cond7.preheader: ; preds = %for.inc10, %for.cond4.preheader
%and.lcssa5 = phi i32 [ %and.lcssa.lcssa7, %for.cond4.preheader ], [ %and, %for.inc10 ]
%b.03 = phi i32 [ 0, %for.cond4.preheader ], [ %inc11, %for.inc10 ]
br label %for.body9, !dbg !39
for.body9: ; preds = %for.body9, %for.cond7.preheader
%and2 = phi i32 [ %and.lcssa5, %for.cond7.preheader ], [ %and, %for.body9 ], !dbg !40
%e.01 = phi i32 [ 0, %for.cond7.preheader ], [ %inc, %for.body9 ]
tail call void @llvm.dbg.value(metadata i32* @c, metadata !19, metadata !DIExpression()), !dbg !40
%and = and i32 %and2, 1, !dbg !32
%inc = add i32 %e.01, 1, !dbg !39
tail call void @llvm.dbg.value(metadata i32 %inc, metadata !18, metadata !DIExpression()), !dbg !42
%exitcond = icmp eq i32 %inc, 30, !dbg !39
br i1 %exitcond, label %for.inc10, label %for.body9, !dbg !39
for.inc10: ; preds = %for.body9
%inc11 = add nsw i32 %b.03, 1, !dbg !38
tail call void @llvm.dbg.value(metadata i32 %inc11, metadata !15, metadata !DIExpression()), !dbg !42
%exitcond11 = icmp eq i32 %inc11, 30, !dbg !38
br i1 %exitcond11, label %for.inc13, label %for.cond7.preheader, !dbg !38
for.inc13: ; preds = %for.inc10
%inc14 = add i32 %d.06, 1, !dbg !37
tail call void @llvm.dbg.value(metadata i32 %inc14, metadata !16, metadata !DIExpression()), !dbg !42
%exitcond12 = icmp eq i32 %inc14, 30, !dbg !37
br i1 %exitcond12, label %for.inc16, label %for.cond4.preheader, !dbg !37
for.inc16: ; preds = %for.inc13
%inc17 = add nsw i32 %a.08, 1, !dbg !31
tail call void @llvm.dbg.value(metadata i32 %inc17, metadata !14, metadata !DIExpression()), !dbg !31
%exitcond13 = icmp eq i32 %inc17, 30, !dbg !31
br i1 %exitcond13, label %for.end18, label %for.cond1.preheader, !dbg !31
for.end18: ; preds = %for.inc16
store i32 %and, i32* @c, align 4, !dbg !32, !tbaa !33
ret void, !dbg !42
}
; Function Attrs: nounwind readnone
declare void @llvm.dbg.value(metadata, metadata, metadata) #1
attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "frame-pointer"="none" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { nounwind readnone }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!26, !43}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, producer: "clang version 3.4 (trunk 191700) (llvm/trunk 191710)", isOptimized: true, splitDebugFilename: "small.dwo", emissionKind: FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "small.c", directory: "/usr/local/google/home/echristo/tmp")
!2 = !{}
!4 = distinct !DISubprogram(name: "bar", line: 18, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: true, unit: !0, scopeLine: 19, file: !1, scope: !5, type: !6, retainedNodes: !2)
!5 = !DIFile(filename: "small.c", directory: "/usr/local/google/home/echristo/tmp")
!6 = !DISubroutineType(types: !7)
!7 = !{null}
!8 = distinct !DISubprogram(name: "foo", line: 2, isLocal: true, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 3, file: !1, scope: !5, type: !9, retainedNodes: !12)
!9 = !DISubroutineType(types: !10)
!10 = !{null, !11}
!11 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!12 = !{!13, !14, !15, !16, !18, !19}
!13 = !DILocalVariable(name: "p", line: 2, arg: 1, scope: !8, file: !5, type: !11)
!14 = !DILocalVariable(name: "a", line: 4, scope: !8, file: !5, type: !11)
!15 = !DILocalVariable(name: "b", line: 4, scope: !8, file: !5, type: !11)
!16 = !DILocalVariable(name: "d", line: 5, scope: !8, file: !5, type: !17)
!17 = !DIBasicType(tag: DW_TAG_base_type, name: "unsigned int", size: 32, align: 32, encoding: DW_ATE_unsigned)
!18 = !DILocalVariable(name: "e", line: 5, scope: !8, file: !5, type: !17)
!19 = !DILocalVariable(name: "w", line: 12, scope: !20, file: !5, type: !25)
!20 = distinct !DILexicalBlock(line: 11, column: 0, file: !1, scope: !21)
!21 = distinct !DILexicalBlock(line: 10, column: 0, file: !1, scope: !22)
!22 = distinct !DILexicalBlock(line: 9, column: 0, file: !1, scope: !23)
!23 = distinct !DILexicalBlock(line: 8, column: 0, file: !1, scope: !24)
!24 = distinct !DILexicalBlock(line: 7, column: 0, file: !1, scope: !8)
!25 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 64, align: 64, baseType: !11)
!26 = !{i32 2, !"Dwarf Version", i32 4}
!27 = !DILocation(line: 20, scope: !4)
!28 = !DILocation(line: 21, scope: !4)
!29 = !{i32 1}
!30 = !DILocation(line: 2, scope: !8)
!31 = !DILocation(line: 7, scope: !24)
!32 = !DILocation(line: 13, scope: !20)
!33 = !{!34, !34, i64 0}
!34 = !{!"int", !35, i64 0}
!35 = !{!"omnipotent char", !36, i64 0}
!36 = !{!"Simple C/C++ TBAA"}
!37 = !DILocation(line: 8, scope: !23)
!38 = !DILocation(line: 9, scope: !22)
!39 = !DILocation(line: 10, scope: !21)
!40 = !DILocation(line: 12, scope: !20)
!41 = !{i32* @c}
!42 = !DILocation(line: 15, scope: !8)
!43 = !{i32 1, !"Debug Info Version", i32 3}
!44 = !{i32 0}
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