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split-comparison llvm pass refactor for smaller compilation times (and a small bug fix) (#964)

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* Refactored split compare pass to be more efficient in LTO usage and allow splitting to other minimum bitwidths.

Efficiency: avoid looping over the whole llvm module N times, when once is also enough.

Bitwidth: Previously, due to fallthrough in switch-case, all comparisons were split to 8-bit, which might not be desirable e.g., 16 or 32 bit might be enough. So now all comparison are split until they are smaller or equal to the target bitwidth, which is controlled through the `AFL_LLVM_LAF_SPLIT_COMPARES_BITW` environment variable.

* fixed miscompilation due to incorrectly trying to split a signed comparison operator

* minor formatting updates and use IRBuilder when inserting multiple instructions

* added @hexcoder-'s test-int_cases.c to make test

* Avoid recursion; switch to smallvector in splitAndSimplify; use switch case for icmp type;

* Fixed issue when splitting < where the inverse comparison was not further split

* some cleanup
This commit is contained in:
Michael Rodler
2021-06-11 11:02:29 +02:00
committed by GitHub
parent b9f260452e
commit 0978c08f4b
3 changed files with 535 additions and 623 deletions
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1105
instrumentation/split-compares-pass.so.cc
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File diff suppressed because it is too large Load Diff

23
test/test-llvm.sh
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@ -186,6 +186,29 @@ test -e ../afl-clang-fast -a -e ../split-switches-pass.so && {
}
rm -f test-instr.plain
$ECHO "$GREY[*] llvm_mode laf-intel/compcov testing splitting integer types (this might take some time)"
for testcase in ./test-int_cases.c ./test-uint_cases.c; do
for I in char short int long "long long"; do
for BITS in 8 16 32 64; do
bin="$testcase-split-$I-$BITS.compcov"
AFL_LLVM_INSTRUMENT=AFL AFL_DEBUG=1 AFL_LLVM_LAF_SPLIT_COMPARES_BITW=$BITS AFL_LLVM_LAF_SPLIT_COMPARES=1 ../afl-clang-fast -DINT_TYPE="$I" -o "$bin" "$testcase" > test.out 2>&1;
if ! test -e "$bin"; then
cat test.out
$ECHO "$RED[!] llvm_mode laf-intel/compcov integer splitting failed! ($testcase with type $I split to $BITS)!";
CODE=1
break
fi
if ! "$bin"; then
$ECHO "$RED[!] llvm_mode laf-intel/compcov integer splitting resulted in miscompilation (type $I split to $BITS)!";
CODE=1
break
fi
rm -f "$bin" test.out || true
done
done
done
rm -f test-int-split*.compcov test.out
AFL_LLVM_INSTRUMENT=AFL AFL_DEBUG=1 AFL_LLVM_LAF_SPLIT_SWITCHES=1 AFL_LLVM_LAF_TRANSFORM_COMPARES=1 AFL_LLVM_LAF_SPLIT_COMPARES=1 ../afl-clang-fast -o test-compcov.compcov test-compcov.c > test.out 2>&1
test -e test-compcov.compcov && test_compcov_binary_functionality ./test-compcov.compcov && {
grep --binary-files=text -Eq " [ 123][0-9][0-9] location| [3-9][0-9] location" test.out && {

30
test/test-uint_cases.c
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@ -1,16 +1,16 @@
/*
* compile with -DUINT_TYPE="unsigned char"
* or -DUINT_TYPE="unsigned short"
* or -DUINT_TYPE="unsigned int"
* or -DUINT_TYPE="unsigned long"
* or -DUINT_TYPE="unsigned long long"
* compile with -DINT_TYPE="char"
* or -DINT_TYPE="short"
* or -DINT_TYPE="int"
* or -DINT_TYPE="long"
* or -DINT_TYPE="long long"
*/
#include <assert.h>
int main() {
volatile UINT_TYPE a, b;
volatile unsigned INT_TYPE a, b;
a = 1;
b = 8;
@ -21,7 +21,7 @@ int main() {
assert((a != b));
assert(!(a == b));
if ((UINT_TYPE)(~0) > 255) {
if ((INT_TYPE)(~0) > 255) {
volatile unsigned short a, b;
a = 256+2;
b = 256+21;
@ -41,7 +41,7 @@ int main() {
assert((a != b));
assert(!(a == b));
if ((UINT_TYPE)(~0) > 65535) {
if ((INT_TYPE)(~0) > 65535) {
volatile unsigned int a, b;
a = 65536+2;
b = 65536+21;
@ -62,7 +62,7 @@ int main() {
assert(!(a == b));
}
if ((UINT_TYPE)(~0) > 4294967295) {
if ((INT_TYPE)(~0) > 4294967295) {
volatile unsigned long a, b;
a = 4294967296+2;
b = 4294967296+21;
@ -93,7 +93,7 @@ int main() {
assert((a != b));
assert(!(a == b));
if ((UINT_TYPE)(~0) > 255) {
if ((INT_TYPE)(~0) > 255) {
volatile unsigned short a, b;
a = 256+2;
b = 256+1;
@ -113,7 +113,7 @@ int main() {
assert((a != b));
assert(!(a == b));
if ((UINT_TYPE)(~0) > 65535) {
if ((INT_TYPE)(~0) > 65535) {
volatile unsigned int a, b;
a = 65536+2;
b = 65536+1;
@ -133,7 +133,7 @@ int main() {
assert((a != b));
assert(!(a == b));
if ((UINT_TYPE)(~0) > 4294967295) {
if ((INT_TYPE)(~0) > 4294967295) {
volatile unsigned long a, b;
a = 4294967296+2;
b = 4294967296+1;
@ -176,7 +176,7 @@ int main() {
assert(!(a != b));
assert((a == b));
if ((UINT_TYPE)(~0) > 255) {
if ((INT_TYPE)(~0) > 255) {
volatile unsigned short a, b;
a = 256+5;
b = 256+5;
@ -187,7 +187,7 @@ int main() {
assert(!(a != b));
assert((a == b));
if ((UINT_TYPE)(~0) > 65535) {
if ((INT_TYPE)(~0) > 65535) {
volatile unsigned int a, b;
a = 65536+5;
b = 65536+5;
@ -198,7 +198,7 @@ int main() {
assert(!(a != b));
assert((a == b));
if ((UINT_TYPE)(~0) > 4294967295) {
if ((INT_TYPE)(~0) > 4294967295) {
volatile unsigned long a, b;
a = 4294967296+5;
b = 4294967296+5;