[lld] [llvm] [Symbolizer] Support for Missing Line Numbers. (PR #82240)

[via llvm-commits]

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+##  Test  --skip-line-zero option.
+##
+##  This test illustrates the usage of handcrafted assembly to produce the following line table.
+##  Address            Line   Column File   ISA Discriminator OpIndex Flags
+##  ------------------ ------ ------ ------ --- ------------- ------- -------------
+##  0x0000000000001710      1      0      2   0             0       0  is_stmt
+##  0x0000000000001717      0     17      2   0             0       0  is_stmt prologue_end
+##  0x000000000000171a      2     15      2   0             0       0
+##  0x000000000000171f      2      3      2   0             0       0  epilogue_begin
+##  0x0000000000001721      2      3      2   0             0       0  end_sequence
+##  0x00000000000016c0      0      0      1   0             0       0  is_stmt
+##  0x00000000000016cf      3     29      1   0             0       0  is_stmt prologue_end
+##  0x00000000000016d5      0     25      1   0             0       0
+##  0x00000000000016da      3     18      1   0             0       0  epilogue_begin
+##  0x00000000000016e0      3     18      1   0             0       0  end_sequence
+
+# REQUIRES: x86-registered-target
+
+# RUN: rm -rf %t && split-file %s %t && cd %t
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux --fdebug-prefix-map=%t="" %s -o %t.o
+
+## Check that without '--skip-line-zero', line number zero is displayed for the line-table entry which has no source correspondence.
+# RUN: llvm-symbolizer --obj=%t.o 0x16d5 | FileCheck --strict-whitespace --match-full-lines --check-prefix=APPROX-DISABLE %s
+
+# APPROX-DISABLE:main
+# APPROX-DISABLE-NEXT:main.c:0:25
+
+## Check that with '--skip-line-zero', the last non-zero line in the current sequence is displayed.
+## If it fails to find in the current sequence then return the original computed line-zero for the queried address.
+# RUN: llvm-symbolizer --obj=%t.o --skip-line-zero 0x16c0 | FileCheck --strict-whitespace --match-full-lines --check-prefix=APPROX-FAIL-ACROSS-SEQ %s
+
+# APPROX-FAIL-ACROSS-SEQ:main
+# APPROX-FAIL-ACROSS-SEQ-NEXT:main.c:0:0
+
+## Check that with '--skip-line-zero', the last non-zero line in the current sequence is displayed.
+# RUN: llvm-symbolizer --obj=%t.o --skip-line-zero 0x1717 | FileCheck --strict-whitespace --match-full-lines --check-prefix=APPROX-WITHIN-SEQ %s
+
+# APPROX-WITHIN-SEQ:foo
+# APPROX-WITHIN-SEQ-NEXT:definitions.c:1:0 (approximate)
+
+## Check to ensure that '--skip-line-zero' only affects addresses having line-zero when more than one address is specified.
+# RUN: llvm-symbolizer --obj=%t.o --skip-line-zero 0x16d5 0x16da | FileCheck --strict-whitespace --match-full-lines --check-prefixes=APPROX-ENABLE,NO-APPROX %s
+
+# APPROX-ENABLE:main
+# APPROX-ENABLE-NEXT:main.c:3:29 (approximate)
+# NO-APPROX:main
+# NO-APPROX-NEXT:main.c:3:18
+
+## Check to ensure that '--skip-line-zero' with '--verbose' enabled displays correct approximate flag in verbose ouptut.
+# RUN: llvm-symbolizer --obj=%t.o --skip-line-zero --verbose 0x1717 | FileCheck --strict-whitespace --match-full-lines --check-prefix=APPROX-VERBOSE %s
+
+# APPROX-VERBOSE:foo
+# APPROX-VERBOSE-NEXT:  Filename: definitions.c
+# APPROX-VERBOSE-NEXT:  Function start filename: definitions.c
+# APPROX-VERBOSE-NEXT:  Function start line: 1
+# APPROX-VERBOSE-NEXT:  Function start address: 0x1710
+# APPROX-VERBOSE-NEXT:  Line: 1
+# APPROX-VERBOSE-NEXT:  Column: 0
+# APPROX-VERBOSE-NEXT:  Approximate: true
+
+## Check to ensure that '--skip-line-zero' with '--output-style=JSON' displays correct approximate flag in JSON output.
+# RUN: llvm-symbolizer --obj=%t.o --skip-line-zero --output-style=JSON 0x1717 | FileCheck --strict-whitespace --match-full-lines --check-prefix=APPROX-JSON %s
+
+# APPROX-JSON:[{"Address":"0x1717","ModuleName":"{{.*}}{{[/|\]+}}test{{[/|\]+}}tools{{[/|\]+}}llvm-symbolizer{{[/|\]+}}Output{{[/|\]+}}skip-line-zero.s.tmp.o","Symbol":[{"Approximate":true,"Column":0,"Discriminator":0,"FileName":"definitions.c","FunctionName":"foo","Line":1,"StartAddress":"0x1710","StartFileName":"definitions.c","StartLine":1}]}]
+
+#--- definitions.c
----------------
bd1976bris wrote:

I would put both foo and main in main.c. That way the dwarf only has to describe a single source file.

https://github.com/llvm/llvm-project/pull/82240