qiongsiwu1 added subscribers: bmahjour, anhtuyen, qiongsiwu1.
qiongsiwu1 added a comment.
Hi everyone! We are encountering crashes in some of our `altivec` test cases
due to this change. `clang` crashes when we have an instance of a `struct` or
`union` type, and we assign the result of a unary operator `++` or `--` with a
vector operand to a field of the instance. If we are assigning the result to
just a vector type, the compiler does not crash.
Here is a reproducer. To reproduce the crash, use command `clang -target
powerpc-unknown-unknown -maltivec small.c`.
// small.c
#include <stdio.h>
// struct type
typedef struct result
{
vector signed short result_vec;
} RESULT;
vector signed short op_nine = { 9, 9, 9, 9, 9, 9, 9, 9 };
int main() {
// Instance of the struct type
RESULT r;
// This line below crashes - we are assigning the result of the unary
operator to a struct field.
r.result_vec = ++op_nine;
for (int i = 0; i < 8; ++i) {
printf("%d\t", r.result_vec[i]);
}
printf("\n");
// This case works fine. The compiler does not crash.
/*vector signed short op_10 = ++op_nine;
for (int i = 0; i < 8; ++i) {
printf("%d\t", op_10[i]);
}
printf("\n"); */
}
We discovered this on AIX and we can reproduce this on Linux on Power. The
issue is reproducible on Intel based Macs as well. Here is a stack dump from
MacOS.
Assertion failed: (isVector() && "Invalid accessor"), function
getVectorLength, file
/Users/qiongsiwu/workspace/community/llvm-project/clang/include/clang/AST/APValue.h,
line 498.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash
backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments:
/Users/qiongsiwu/workspace/community/llvm-project/build/bin/clang-14 -cc1
-triple powerpc-unknown-unknown -emit-obj -mrelax-all --mrelax-relocations
-disable-free -clear-ast-before-backend -main-file-name small.c
-mrelocation-model static -mframe-pointer=all -fmath-errno -ffp-contract=on
-fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu ppc
-target-feature +altivec -mfloat-abi hard -debugger-tuning=gdb
-target-linker-version 650.9
-fcoverage-compilation-dir=/Users/qiongsiwu/workspace/13359 -resource-dir
/Users/qiongsiwu/workspace/community/llvm-project/build/lib/clang/14.0.0 -I
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/include/
-fdebug-compilation-dir=/Users/qiongsiwu/workspace/13359 -ferror-limit 19
-fno-signed-char -fgnuc-version=4.2.1 -fcolor-diagnostics -faddrsig
-D__GCC_HAVE_DWARF2_CFI_ASM=1 -o
/var/folders/gh/5hw84m4x2hv4csmhpp8y02680000gn/T/small-e9e02b.o -x c small.c
1. small.c:23:5: current parser token 'return'
2. small.c:12:12: parsing function body 'main'
3. small.c:12:12: in compound statement ('{}')
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH
or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0 clang-14 0x0000000107d8d1f7
llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 39
1 clang-14 0x0000000107d8bfb8 llvm::sys::RunSignalHandlers()
+ 248
2 clang-14 0x0000000107d8d840 SignalHandler(int) + 272
3 libsystem_platform.dylib 0x00007ff80662fe2d _sigtramp + 29
4 libsystem_platform.dylib 0x00007ff7ba7632d0 _sigtramp +
18446744072435741888
5 libsystem_c.dylib 0x00007ff806566d10 abort + 123
6 libsystem_c.dylib 0x00007ff8065660be err + 0
7 clang-14 0x000000010c208443 (anonymous
namespace)::VectorExprEvaluator::VisitUnaryOperator(clang::UnaryOperator
const*) (.cold.13) + 35
8 clang-14 0x000000010a40b1d7 (anonymous
namespace)::VectorExprEvaluator::VisitUnaryOperator(clang::UnaryOperator
const*) + 2375
On AIX, the compiler can produce the following AST during `EvaluateVector`
before the crash.
[EvaluateVector]
BinaryOperator 0x11173e148 '__vector short' '='
|-MemberExpr 0x11173e0e0 '__vector short' lvalue .result_vec 0x111739f40
| `-DeclRefExpr 0x11173a5a0 'RESULT':'struct result' lvalue Var 0x11173a520
'r' 'RESULT':'struct result'
`-UnaryOperator 0x11173e130 '__vector short' prefix '++'
`-DeclRefExpr 0x11173e110 '__vector short' lvalue Var 0x11173a070 'op_nine'
'__vector short'
[EvaluateVector]
UnaryOperator 0x11173e130 '__vector short' prefix '++'
`-DeclRefExpr 0x11173e110 '__vector short' lvalue Var 0x11173a070 'op_nine'
'__vector short'
The compiler crashes when trying to deal with `0x11173a070`. It is expecting a
vector kind (`APValue::ValueKind::Vector`), but the actual kind is
`APValue::ValueKind::LValue`, and the compiler crashes inside
`SubExprValue.getVectorLength()`.
Could you help us take a look? Thanks a lot! FYI @bmahjour @anhtuyen
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D115670/new/
https://reviews.llvm.org/D115670
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