aaron.ballman added a comment.
Intel is seeing some fallout from this change in our downstream (reverting this
commit causes our test case to pass). Our test looks like this:
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <x86intrin.h>
typedef union {
char c[32];
short s[16];
int d[8];
long long l[4];
__m128 h[2];
__m256 m;
__m256i mi;
__m256d md;
} M256;
M256 make_m256_from_int(int d1, int d2, int d3, int d4, int d5, int d6, int
d7, int d8) {
M256 ret;
ret.d[0] = d1;
ret.d[1] = d2;
ret.d[2] = d3;
ret.d[3] = d4;
ret.d[4] = d5;
ret.d[5] = d6;
ret.d[6] = d7;
ret.d[7] = d8;
return ret;
}
typedef union {
char c;
} M8;
M8 make_m8_from_char(char c) {
M8 ret;
ret.c = c;
return ret;
}
int test(char* format, ...) {
int i, j;
M256 m256;
M8 m8;
int retValue = 0;
va_list args;
va_start(args, format);
for (i = 0; format[i]; i++) {
switch (format[i]) {
case '1':
m8 = va_arg(args, M8);
retValue += m8.c;
break;
case '6':
m256 = va_arg(args, M256);
retValue += m256.d[0] + m256.d[1] + m256.d[2] +
m256.d[3] + m256.d[4] + m256.d[5] + m256.d[6] + m256.d[7];
break;
}
}
va_end(args);
return retValue;
}
int main(void) {
int retValue = 0;
if (test("16", make_m8_from_char(-12), make_m256_from_int(1, 2, 1, 2,
1, 2, 1, 2))) {
fprintf(stderr, "test failed for: M8(%d)
M256(%d,%d,%d,%d,%d,%d,%d,%d)\n", 12, 1, 2, 1, 2, 1, 2, 1, 2);
retValue++;
}
if (retValue) {
printf("FAILED %d tests\n", retValue);
} else {
printf("PASSED\n");
}
return retValue;
}
What we're seeing is the difference in IR emitted by FE is the byval attribute
and alignment for 3rd argument.
Bad
%call2 = call i32 (ptr, ...) @test(ptr noundef @"??_C@_02KMALDIDP@16?$AA@",
ptr noundef byval(%union.M8) align 4 %agg.tmp1, ptr noundef %agg.tmp), !dbg !237
Good
%call2 = call i32 (ptr, ...) @test(ptr noundef @"??_C@_02KMALDIDP@16?$AA@",
ptr noundef byval(%union.M8) align 4 %agg.tmp1, ptr noundef byval(%union.M256)
align 4 %agg.tmp), !dbg !237
(We're seeing it with this clang-cl-esque command line: `icx -c -Zi -Od
/arch:AVX check_types_reduced.c -Xclang -emit-llvm -Xclang
-disable-llvm-passes`)
I didn't spot any UB in the test, so I think something may be incorrect with
this patch (but codegen is not my area of specialty, so please correct me if
I'm wrong).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D152752/new/
https://reviews.llvm.org/D152752
_______________________________________________
cfe-commits mailing list
cfe-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
