[llvm] 2c07181 - [LEB128] Don't initialize error on success
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Wed Nov 29 12:48:18 PST 2023
Author: Adrian Prantl
Date: 2023-11-29T12:47:27-08:00
New Revision: 2c07181424b45d0785002b760f9ab404b7506b57
URL: https://github.com/llvm/llvm-project/commit/2c07181424b45d0785002b760f9ab404b7506b57
DIFF: https://github.com/llvm/llvm-project/commit/2c07181424b45d0785002b760f9ab404b7506b57.diff
LOG: [LEB128] Don't initialize error on success
This change removes an unnecessary branch from a hot path. It's also
questionable API to override any previous error unconditonally.
Added:
Modified:
lld/COFF/Driver.cpp
lld/ELF/Driver.cpp
llvm/include/llvm/Support/LEB128.h
llvm/lib/Object/MachOObjectFile.cpp
llvm/lib/Support/DataExtractor.cpp
llvm/tools/llvm-readobj/COFFDumper.cpp
llvm/tools/llvm-readobj/ELFDumper.cpp
Removed:
################################################################################
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index f5cb379c5a4bf95..327df6078fef546 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -1258,7 +1258,7 @@ static void findKeepUniqueSections(COFFLinkerContext &ctx) {
const uint8_t *cur = contents.begin();
while (cur != contents.end()) {
unsigned size;
- const char *err;
+ const char *err = nullptr;
uint64_t symIndex = decodeULEB128(cur, &size, contents.end(), &err);
if (err)
fatal(toString(obj) + ": could not decode addrsig section: " + err);
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index 6290880c43d3b95..6bef09eeca015aa 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -2296,7 +2296,7 @@ static void findKeepUniqueSections(opt::InputArgList &args) {
const uint8_t *cur = contents.begin();
while (cur != contents.end()) {
unsigned size;
- const char *err;
+ const char *err = nullptr;
uint64_t symIndex = decodeULEB128(cur, &size, contents.end(), &err);
if (err)
fatal(toString(f) + ": could not decode addrsig section: " + err);
diff --git a/llvm/include/llvm/Support/LEB128.h b/llvm/include/llvm/Support/LEB128.h
index a5d367279aefe64..7ec19fee5d8ba51 100644
--- a/llvm/include/llvm/Support/LEB128.h
+++ b/llvm/include/llvm/Support/LEB128.h
@@ -125,14 +125,15 @@ inline unsigned encodeULEB128(uint64_t Value, uint8_t *p,
}
/// Utility function to decode a ULEB128 value.
+///
+/// If \p error is non-null, it will point to a static error message,
+/// if an error occured. It will not be modified on success.
inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = nullptr,
const uint8_t *end = nullptr,
const char **error = nullptr) {
const uint8_t *orig_p = p;
uint64_t Value = 0;
unsigned Shift = 0;
- if (error)
- *error = nullptr;
do {
if (p == end) {
if (error)
@@ -158,6 +159,9 @@ inline uint64_t decodeULEB128(const uint8_t *p, unsigned *n = nullptr,
}
/// Utility function to decode a SLEB128 value.
+///
+/// If \p error is non-null, it will point to a static error message,
+/// if an error occured. It will not be modified on success.
inline int64_t decodeSLEB128(const uint8_t *p, unsigned *n = nullptr,
const uint8_t *end = nullptr,
const char **error = nullptr) {
@@ -165,8 +169,6 @@ inline int64_t decodeSLEB128(const uint8_t *p, unsigned *n = nullptr,
int64_t Value = 0;
unsigned Shift = 0;
uint8_t Byte;
- if (error)
- *error = nullptr;
do {
if (p == end) {
if (error)
diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index aa57de16ed18f44..5e6c6ea79427537 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -2996,7 +2996,7 @@ void ExportEntry::pushNode(uint64_t offset) {
ErrorAsOutParameter ErrAsOutParam(E);
const uint8_t *Ptr = Trie.begin() + offset;
NodeState State(Ptr);
- const char *error;
+ const char *error = nullptr;
uint64_t ExportInfoSize = readULEB128(State.Current, &error);
if (error) {
*E = malformedError("export info size " + Twine(error) +
@@ -3131,7 +3131,7 @@ void ExportEntry::pushNode(uint64_t offset) {
void ExportEntry::pushDownUntilBottom() {
ErrorAsOutParameter ErrAsOutParam(E);
- const char *error;
+ const char *error = nullptr;
while (Stack.back().NextChildIndex < Stack.back().ChildCount) {
NodeState &Top = Stack.back();
CumulativeString.resize(Top.ParentStringLength);
diff --git a/llvm/lib/Support/DataExtractor.cpp b/llvm/lib/Support/DataExtractor.cpp
index 59a44f4071b5fa0..eac3c32cfd3b796 100644
--- a/llvm/lib/Support/DataExtractor.cpp
+++ b/llvm/lib/Support/DataExtractor.cpp
@@ -202,7 +202,7 @@ static T getLEB128(StringRef Data, uint64_t *OffsetPtr, Error *Err,
if (isError(Err))
return T();
- const char *error;
+ const char *error = nullptr;
unsigned bytes_read;
T result =
Decoder(Bytes.data() + *OffsetPtr, &bytes_read, Bytes.end(), &error);
diff --git a/llvm/tools/llvm-readobj/COFFDumper.cpp b/llvm/tools/llvm-readobj/COFFDumper.cpp
index 9c24b0b8db35f1e..3ad40dc3551085a 100644
--- a/llvm/tools/llvm-readobj/COFFDumper.cpp
+++ b/llvm/tools/llvm-readobj/COFFDumper.cpp
@@ -2126,7 +2126,7 @@ void COFFDumper::printAddrsig() {
const uint8_t *End = AddrsigContents.bytes_end();
while (Cur != End) {
unsigned Size;
- const char *Err;
+ const char *Err = nullptr;
uint64_t SymIndex = decodeULEB128(Cur, &Size, End, &Err);
if (Err)
reportError(createError(Err), Obj->getFileName());
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index ab26f1369407bf2..d6d0ea35044ab30 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -5004,7 +5004,7 @@ static Expected<std::vector<uint64_t>> toULEB128Array(ArrayRef<uint8_t> Data) {
const uint8_t *End = Data.end();
while (Cur != End) {
unsigned Size;
- const char *Err;
+ const char *Err = nullptr;
Ret.push_back(decodeULEB128(Cur, &Size, End, &Err));
if (Err)
return createError(Err);
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