Allow .alt_entry symbols to pass the .cfi nesting check#82268
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@llvm/pr-subscribers-mc @llvm/pr-subscribers-backend-aarch64 Author: Jon Roelofs (jroelofs) ChangesFixes: #82261 Full diff: https://github.com/llvm/llvm-project/pull/82268.diff 2 Files Affected:
diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index 8e508dbdb1c69b..e8dc078c9610c2 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -44,6 +44,7 @@
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCSymbolMachO.h"
#include "llvm/MC/MCTargetOptions.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Casting.h"
@@ -1950,7 +1951,9 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
Lex();
}
- if (MAI.hasSubsectionsViaSymbols() && CFIStartProcLoc && Sym->isExternal())
+ if (MAI.hasSubsectionsViaSymbols() && CFIStartProcLoc &&
+ Sym->isExternal() &&
+ (!isa<MCSymbolMachO>(Sym) || !cast<MCSymbolMachO>(Sym)->isAltEntry()))
return Error(StartTokLoc, "non-private labels cannot appear between "
".cfi_startproc / .cfi_endproc pairs") &&
Error(*CFIStartProcLoc, "previous .cfi_startproc was here");
diff --git a/llvm/test/MC/AArch64/cfi-bad-nesting-darwin.s b/llvm/test/MC/AArch64/cfi-bad-nesting-darwin.s
index 235b7d44809929..6a4dda3a77f05a 100644
--- a/llvm/test/MC/AArch64/cfi-bad-nesting-darwin.s
+++ b/llvm/test/MC/AArch64/cfi-bad-nesting-darwin.s
@@ -8,6 +8,8 @@
.p2align 2
_locomotive:
.cfi_startproc
+ .alt_entry _engineer
+_engineer:
ret
; It is invalid to have a non-private label between .cfi_startproc and
@@ -17,7 +19,7 @@ _locomotive:
.p2align 2
_caboose:
; DARWIN: [[#@LINE-1]]:1: error: non-private labels cannot appear between .cfi_startproc / .cfi_endproc pairs
-; DARWIN: [[#@LINE-10]]:2: error: previous .cfi_startproc was here
+; DARWIN: [[#@LINE-12]]:2: error: previous .cfi_startproc was here
ret
.cfi_endproc
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MaskRay
reviewed
Feb 24, 2024
| if (MAI.hasSubsectionsViaSymbols() && CFIStartProcLoc && Sym->isExternal()) | ||
| if (MAI.hasSubsectionsViaSymbols() && CFIStartProcLoc && | ||
| Sym->isExternal() && | ||
| (!isa<MCSymbolMachO>(Sym) || !cast<MCSymbolMachO>(Sym)->isAltEntry())) |
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Since only MCAsmInfoDarwin sets hasSubsectionsViaSymbols. The isa<MCSymbolMachO>(Sym) check is unneeded.
MaskRay
approved these changes
Feb 24, 2024
| .p2align 2 | ||
| _locomotive: | ||
| .cfi_startproc | ||
| .alt_entry _engineer |
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Add a comment that a N_ALT_ENTRY symbol can be in the middle of a subsection?
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This is a good candidate for release/18.x |
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/cherry-pick 5b91647 |
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Error: Command failed due to missing milestone. |
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/cherry-pick 5b91647 |
llvmbot
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Feb 28, 2024
A symbol with an `N_ALT_ENTRY` attribute may be defined in the middle of
a subsection, so it is reasonable to opt them out of the
`.cfi_{start,end}proc` nesting check.
Fixes: llvm#82261
(cherry picked from commit 5b91647)
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/pull-request #83336 |
llvmbot
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Mar 11, 2024
A symbol with an `N_ALT_ENTRY` attribute may be defined in the middle of
a subsection, so it is reasonable to opt them out of the
`.cfi_{start,end}proc` nesting check.
Fixes: llvm#82261
(cherry picked from commit 5b91647)
Closed
MaskRay
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Jul 2, 2024
The current `setAtom` is inaccurate: a `.alt_entry` label can also be recognized as an atom. This is mostly benign, but might cause two locations only separated by an `.alt_entry` to have different atoms. https://reviews.llvm.org/D153167 changed a `evaluateKnownAbsolute` to `evaluateAsAbsolute` and would not fold `A-B` even if they are only separated by a `.alt_entry` label, leading to a spurious error `invalid CFI advance_loc expression`. The fix is similar to #82268: add a special case for `.alt_entry`. Fix #97116 Pull Request: #97479
mylai-mtk
pushed a commit
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Jul 12, 2024
A symbol with an `N_ALT_ENTRY` attribute may be defined in the middle of
a subsection, so it is reasonable to opt them out of the
`.cfi_{start,end}proc` nesting check.
Fixes: llvm#82261
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A symbol with an
N_ALT_ENTRYattribute may be defined in the middle of a subsection, so it is reasonable to opt them out of the.cfi_{start,end}procnesting check.Fixes: #82261