[llvm-branch-commits] [llvm] 3ca502a - Use DataExtractor to decode SLEB128 in android_relas.
Author: Rahman Lavaee
Date: 2021-01-28T01:35:18-08:00
New Revision: 3ca502a7d60787abe14db1fa541950ff79c7585b
URL:
https://github.com/llvm/llvm-project/commit/3ca502a7d60787abe14db1fa541950ff79c7585b
DIFF:
https://github.com/llvm/llvm-project/commit/3ca502a7d60787abe14db1fa541950ff79c7585b.diff
LOG: Use DataExtractor to decode SLEB128 in android_relas.
A simple refactoring patch which let us use `DataExtractor::getSLEB128` rather
than using a lambda function.
Differential Revision: https://reviews.llvm.org/D95158
Added:
Modified:
llvm/lib/Object/ELF.cpp
llvm/test/tools/llvm-readobj/ELF/packed-relocs-errors.s
Removed:
diff --git a/llvm/lib/Object/ELF.cpp b/llvm/lib/Object/ELF.cpp
index 264f115ddbb5..27a35bbd759d 100644
--- a/llvm/lib/Object/ELF.cpp
+++ b/llvm/lib/Object/ELF.cpp
@@ -8,7 +8,7 @@
#include "llvm/Object/ELF.h"
#include "llvm/BinaryFormat/ELF.h"
-#include "llvm/Support/LEB128.h"
+#include "llvm/Support/DataExtractor.h"
using namespace llvm;
using namespace object;
@@ -373,39 +373,31 @@ ELFFile::android_relas(const Elf_Shdr &Sec) const {
Expected> ContentsOrErr = getSectionContents(Sec);
if (!ContentsOrErr)
return ContentsOrErr.takeError();
- const uint8_t *Cur = ContentsOrErr->begin();
- const uint8_t *End = ContentsOrErr->end();
- if (ContentsOrErr->size() < 4 || Cur[0] != 'A' || Cur[1] != 'P' ||
- Cur[2] != 'S' || Cur[3] != '2')
+ ArrayRef Content = *ContentsOrErr;
+ if (Content.size() < 4 || Content[0] != 'A' || Content[1] != 'P' ||
+ Content[2] != 'S' || Content[3] != '2')
return createError("invalid packed relocation header");
- Cur += 4;
-
- const char *ErrStr = nullptr;
- auto ReadSLEB = [&]() -> int64_t {
-if (ErrStr)
- return 0;
-unsigned Len;
-int64_t Result = decodeSLEB128(Cur, &Len, End, &ErrStr);
-Cur += Len;
-return Result;
- };
+ DataExtractor Data(Content, isLE(), ELFT::Is64Bits ? 8 : 4);
+ DataExtractor::Cursor Cur(/*Offset=*/4);
- uint64_t NumRelocs = ReadSLEB();
- uint64_t Offset = ReadSLEB();
+ uint64_t NumRelocs = Data.getSLEB128(Cur);
+ uint64_t Offset = Data.getSLEB128(Cur);
uint64_t Addend = 0;
- if (ErrStr)
-return createError(ErrStr);
+ if (!Cur)
+return std::move(Cur.takeError());
std::vector Relocs;
Relocs.reserve(NumRelocs);
while (NumRelocs) {
-uint64_t NumRelocsInGroup = ReadSLEB();
+uint64_t NumRelocsInGroup = Data.getSLEB128(Cur);
+if (!Cur)
+ return std::move(Cur.takeError());
if (NumRelocsInGroup > NumRelocs)
return createError("relocation group unexpectedly large");
NumRelocs -= NumRelocsInGroup;
-uint64_t GroupFlags = ReadSLEB();
+uint64_t GroupFlags = Data.getSLEB128(Cur);
bool GroupedByInfo = GroupFlags & ELF::RELOCATION_GROUPED_BY_INFO_FLAG;
bool GroupedByOffsetDelta = GroupFlags &
ELF::RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG;
bool GroupedByAddend = GroupFlags & ELF::RELOCATION_GROUPED_BY_ADDEND_FLAG;
@@ -413,34 +405,30 @@ ELFFile::android_relas(const Elf_Shdr &Sec) const {
uint64_t GroupOffsetDelta;
if (GroupedByOffsetDelta)
- GroupOffsetDelta = ReadSLEB();
+ GroupOffsetDelta = Data.getSLEB128(Cur);
uint64_t GroupRInfo;
if (GroupedByInfo)
- GroupRInfo = ReadSLEB();
+ GroupRInfo = Data.getSLEB128(Cur);
if (GroupedByAddend && GroupHasAddend)
- Addend += ReadSLEB();
+ Addend += Data.getSLEB128(Cur);
if (!GroupHasAddend)
Addend = 0;
-for (uint64_t I = 0; I != NumRelocsInGroup; ++I) {
+for (uint64_t I = 0; Cur && I != NumRelocsInGroup; ++I) {
Elf_Rela R;
- Offset += GroupedByOffsetDelta ? GroupOffsetDelta : ReadSLEB();
+ Offset += GroupedByOffsetDelta ? GroupOffsetDelta : Data.getSLEB128(Cur);
R.r_offset = Offset;
- R.r_info = GroupedByInfo ? GroupRInfo : ReadSLEB();
+ R.r_info = GroupedByInfo ? GroupRInfo : Data.getSLEB128(Cur);
if (GroupHasAddend && !GroupedByAddend)
-Addend += ReadSLEB();
+Addend += Data.getSLEB128(Cur);
R.r_addend = Addend;
Relocs.push_back(R);
-
- if (ErrStr)
-return createError(ErrStr);
}
-
-if (ErrStr)
- return createError(ErrStr);
+if (!Cur)
+ return std::move(Cur.takeError());
}
return Relocs;
diff --git a/llvm/test/tools/llvm-readobj/ELF/packed-relocs-errors.s
b/llvm/test/tools/llvm-readobj/ELF/packed-relocs-errors.s
index 4f2e65ed220f..32e96d716ca4 100644
--- a/llvm/test/tools/llvm-readobj/ELF/packed-relocs-errors.s
+++ b/llvm/test/tools/llvm-readobj/ELF/packed-relocs-errors.s
@@ -23,7 +23,7 @@
.section .rela.dyn, "a", @0x6001
.ascii "APS2"
-# ERR-PAST-END: warning: '[[FILE]]': unable to read relocations from
SHT_ANDROID_REL section with index 3: malformed sleb128, extends past end
+# ERR-PAST-END: warning: '[[FILE]]': unable to read relocations from
SH
Re: [llvm-branch-commits] [clang] c3a21e5 - [ASTMatchers] Ensure that we can match inside lambdas
Thanks for the prompt response!
On Thu, Jan 28, 2021 at 12:52 AM Stephen Kelly wrote:
>
> Thanks for reporting. Please try https://reviews.llvm.org/D95573
>
> Thanks,
>
> Stephen.
> On 27/01/2021 22:58, Alexander Kornienko wrote:
>
> This patch causes practically infinite traversal times on code that
> contains deeply nested lambdas. Please fix or revert the commit.
>
> There's a very simple test case (add more nesting, if it's still fast ;):
>
> void f() {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> [] {
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }();
> }
>
> Three nested lambdas are enough to demonstrate the issue by looking at the
> AST dump. The body of the innermost lambda (0x45593fda99a0) is printed 8
> times, and it will be traversed 8 times as well by AST matchers:
> `-FunctionDecl 0x45593fda9198
> line:1:6 f 'void ()'
> `-CompoundStmt 0x45593fdce970
> `-ExprWithCleanups 0x45593fdce958 'void':'void'
> `-CXXOperatorCallExpr 0x45593fdce928
> 'void':'void' '()'
> |-ImplicitCastExpr 0x45593fdce8b0 'auto (*)() const
> -> void'
> | `-DeclRefExpr 0x45593fdce890 'auto () const ->
> void' lvalue CXXMethod 0x45593fda9490 'operator()' 'auto () const -> void'
> `-ImplicitCastExpr 0x45593fdce910 'const
> (lambda at /tmp/nested-lambdas.cc:2:3)' lvalue
> `-MaterializeTemporaryExpr 0x45593fdce8f8
> '(lambda at /tmp/nested-lambdas.cc:2:3)' lvalue
> `-LambdaExpr 0x45593fdce788 '(lambda at
> /tmp/nested-lambdas.cc:2:3)'
> |-CXXRecordDecl 0x45593fda9350 col:3 implicit
> class definition
> | |-DefinitionData lambda pass_in_registers empty
> standard_layout trivially_copyable literal can_const_default_init
> | | |-DefaultConstructor defaulted_is_constexpr
> | | |-CopyConstructor simple trivial has_const_param
> needs_implicit implicit_has_const_param
> | | |-MoveConstructor exists simple trivial needs_implicit
> | | |-CopyAssignment trivial has_const_param needs_implicit
> implicit_has_const_param
> | | |-MoveAssignment
> | | `-Destructor simple irrelevant trivial
> | |-CXXMethodDecl 0x45593fda9490 line:2:3
> used constexpr operator() 'auto () const -> void' inline
> | | `-CompoundStmt 0x45593fdce4e0
> | | `-ExprWithCleanups 0x45593fdce4c8
> 'void':'void'
> | | `-CXXOperatorCallExpr 0x45593fdce498 line:6:5> 'void':'void' '()'
> | | |-ImplicitCastExpr 0x45593fdce420
> 'auto (*)() const -> void'
> | | | `-DeclRefExpr 0x45593fdce400
> 'auto () const -> void' lvalue CXXMethod 0x45593fda96c0 'operator()' 'auto
> () const -> void'
> | | `-ImplicitCastExpr 0x45593fdce480 line:6:3> 'const (lambda at /tmp/nested-lambdas.cc:3:3)' lvalue
> | | `-MaterializeTemporaryExpr 0x45593fdce468
> '(lambda at /tmp/nested-lambdas.cc:3:3)' lvalue
> | | `-LambdaExpr 0x45593fdce2f0 line:6:3> '(lambda at /tmp/nested-lambdas.cc:3:3)'
> | | |-CXXRecordDecl 0x45593fda9588
> col:3 implicit class definition
> | | | |-DefinitionData lambda pass_in_registers
> empty standard_layout trivially_copyable literal can_const_default_init
> | | | | |-DefaultConstructor
> defaulted_is_constexpr
> | | | | |-CopyConstructor simple trivial
> has_const_param needs_implicit implicit_has_const_param
> | | | | |-MoveConstructor exists simple trivial
> needs_implicit
> | | | | |-CopyAssignment trivial has_const_param
> needs_implicit implicit_has_const_param
> | | | | |-MoveAssignment
> | | | | `-Destructor simple irrelevant trivial
> | | | |-CXXMethodDecl 0x45593fda96c0 line:6:3> line:3:3 used constexpr operator() 'auto () const -> void' inline
> | | | | `-CompoundStmt 0x45593fdce048 line:6:3>
> | | | | `-ExprWithCleanups 0x45593fdce030
> 'void':'void'
> | | | | `-CXXOperatorCallExpr 0x45593fdce000
> 'void':'void' '()'
> | | | | |-ImplicitCastExpr 0x45593fda9f88
> 'auto (*)() const -> void'
> | | | | | `-DeclRefExpr 0x45593fda9f08
> 'auto () const -> void' lvalue CXXMethod 0x45593fda98f0
> 'operator()' 'auto () c
