MC: Evaluate .org during fragment relaxation
Similar to 742ecfc13e8aa34cfff2900e31838f657fcafe30 for MCFillFragment,
ensure `.org` directives with expressions are re-evaluated during
fragment relaxation, as their sizes may change. Continue iteration to
prevent stale, incorrect sizes. While I knew MCOrgFragment likely needed
to be re-evaluated at all, I did not have a motivation to add it;-)
This fixes the root cause of
https://github.com/ClangBuiltLinux/linux/issues/2116
(writeSectionData assertion failure when building the Linux kernel for arm64)
The issue cannot be reliably replicated. The specific test case would
not replicate if any of the following condition was not satisfied:
* .org was not re-evaluated. Fixed by this commit.
* clang -cc1as has a redundant `initSections` call, leading to a
redundant initial FT_Align fragment. llvm-mc -filetype=obj, lacking
the redundant `initSections`, doesn't replicate.
* faa931b717c02d57f0814caa9133219040e6a85b decreased sizeof(MCFragment).
* f1aa6050bd90f8ec4273da55d362e23905ad3a81 added more fragments
diff --git a/llvm/include/llvm/MC/MCAssembler.h b/llvm/include/llvm/MC/MCAssembler.h
index ffde5ca2..afd38d2 100644
--- a/llvm/include/llvm/MC/MCAssembler.h
+++ b/llvm/include/llvm/MC/MCAssembler.h
@@ -120,6 +120,7 @@
bool relaxCVInlineLineTable(MCCVInlineLineTableFragment &DF);
bool relaxCVDefRange(MCCVDefRangeFragment &DF);
bool relaxFill(MCFillFragment &F);
+ bool relaxOrg(MCOrgFragment &F);
public:
/// Construct a new assembler instance.
diff --git a/llvm/include/llvm/MC/MCSection.h b/llvm/include/llvm/MC/MCSection.h
index 493bd11..cc191ae 100644
--- a/llvm/include/llvm/MC/MCSection.h
+++ b/llvm/include/llvm/MC/MCSection.h
@@ -383,13 +383,16 @@
/// Source location of the directive that this fragment was created for.
SMLoc Loc;
+ uint64_t Size = 0;
+
public:
MCOrgFragment(const MCExpr &Offset, int8_t Value, SMLoc Loc)
: MCFragment(FT_Org), Value(Value), Offset(&Offset), Loc(Loc) {}
const MCExpr &getOffset() const { return *Offset; }
-
uint8_t getValue() const { return Value; }
+ uint64_t getSize() const { return Size; }
+ void setSize(uint64_t Value) { Size = Value; }
SMLoc getLoc() const { return Loc; }
diff --git a/llvm/lib/MC/MCAssembler.cpp b/llvm/lib/MC/MCAssembler.cpp
index 5c8e904..d172ad1 100644
--- a/llvm/lib/MC/MCAssembler.cpp
+++ b/llvm/lib/MC/MCAssembler.cpp
@@ -945,6 +945,14 @@
return true;
}
+bool MCAssembler::relaxOrg(MCOrgFragment &F) {
+ uint64_t Size = computeFragmentSize(F);
+ if (F.getSize() == Size)
+ return false;
+ F.setSize(Size);
+ return true;
+}
+
bool MCAssembler::relaxFragment(MCFragment &F) {
switch(F.getKind()) {
default:
@@ -966,6 +974,8 @@
return relaxCVDefRange(cast<MCCVDefRangeFragment>(F));
case MCFragment::FT_Fill:
return relaxFill(cast<MCFillFragment>(F));
+ case MCFragment::FT_Org:
+ return relaxOrg(static_cast<MCOrgFragment &>(F));
}
}
diff --git a/llvm/test/MC/ELF/mc-dump.s b/llvm/test/MC/ELF/mc-dump.s
index 51b3ff4..a590e1c 100644
--- a/llvm/test/MC/ELF/mc-dump.s
+++ b/llvm/test/MC/ELF/mc-dump.s
@@ -30,7 +30,7 @@
# CHECK-NEXT:5 LEB Size:0+1 [15] Value:.Ltmp0-_start Signed:0
# CHECK:]
-# CHECK: 2 assembler - Number of fixup evaluations for relaxation
+# CHECK: 3 assembler - Number of fixup evaluations for relaxation
# CHECK: 8 assembler - Number of fixups
# RUN: llvm-mc -filetype=obj -triple=x86_64 %s -o %t -debug-only=mc-dump -save-temp-labels -g 2>&1 | FileCheck %s --check-prefix=CHECK2
