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[gcov] Fix gcov profiling on big-endian machines 

Two fixes required to handle big-endian systems:

- 64-bit counter values are stored in a mixed-endian format in the
gcov files: a 32-bit low-part followed by a 32-bit high part. Note that
this is already implemented correctly on the LLVM side, see
GCOVBuffer::readInt64.

- The tag values (e.g. arcs tag, object summary tag, ...) are aways
written as the same sequence of bytes independent of byte order. But
when *reading* them back in, the code reads them as 32-bit values in
host byte order. For the comparisons to work correctly, this should
instead always read them as little-endian values.

Fixes PR 38121.

Reviewed By: marco-c

Differential Revision: https://reviews.llvm.org/D49132

llvm-svn: 336693
This commit is contained in:
Ulrich Weigand 2018-07-10 16:08:27 +00:00
parent b961fdc509
commit e508cd2a04
1 changed files with 21 additions and 8 deletions
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29
compiler-rt/lib/profile/GCDAProfiling.c
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@ -178,7 +178,12 @@ static void write_32bit_value(uint32_t i) {
} }
static void write_64bit_value(uint64_t i) { static void write_64bit_value(uint64_t i) {
write_bytes((char*)&i, 8); // GCOV uses a lo-/hi-word format even on big-endian systems.
// See also GCOVBuffer::readInt64 in LLVM.
uint32_t lo = (uint32_t) i;
uint32_t hi = (uint32_t) (i >> 32);
write_32bit_value(lo);
write_32bit_value(hi);
} }
static uint32_t length_of_string(const char *s) { static uint32_t length_of_string(const char *s) {
@ -203,17 +208,25 @@ static uint32_t read_32bit_value() {
return val; return val;
} }
static uint64_t read_64bit_value() { static uint32_t read_le_32bit_value() {
uint64_t val; uint32_t val = 0;
if (new_file) if (new_file)
return (uint64_t)-1; return (uint32_t)-1;
val = *(uint64_t*)&write_buffer[cur_pos]; for (int i = 0; i < 4; i++)
cur_pos += 8; val |= write_buffer[cur_pos++] << (8*i);
return val; return val;
} }
static uint64_t read_64bit_value() {
// GCOV uses a lo-/hi-word format even on big-endian systems.
// See also GCOVBuffer::readInt64 in LLVM.
uint32_t lo = read_32bit_value();
uint32_t hi = read_32bit_value();
return ((uint64_t)hi << 32) | ((uint64_t)lo);
}
static char *mangle_filename(const char *orig_filename) { static char *mangle_filename(const char *orig_filename) {
char *new_filename; char *new_filename;
size_t prefix_len; size_t prefix_len;
@ -400,7 +413,7 @@ void llvm_gcda_emit_arcs(uint32_t num_counters, uint64_t *counters) {
if (!output_file) return; if (!output_file) return;
val = read_32bit_value(); val = read_le_32bit_value();
if (val != (uint32_t)-1) { if (val != (uint32_t)-1) {
/* There are counters present in the file. Merge them. */ /* There are counters present in the file. Merge them. */
@ -454,7 +467,7 @@ void llvm_gcda_summary_info() {
if (!output_file) return; if (!output_file) return;
val = read_32bit_value(); val = read_le_32bit_value();
if (val != (uint32_t)-1) { if (val != (uint32_t)-1) {
/* There are counters present in the file. Merge them. */ /* There are counters present in the file. Merge them. */