As noted in the D44909 review, the transform from (fptosi+sitofp) to ftrunc
can produce -0.0 where the original code does not:
#include <stdio.h>
int main(int argc) {
float x;
x = -0.8 * argc;
printf("%f\n", (float)((int)x));
return 0;
}
$ clang -O0 -mavx fp.c ; ./a.out
0.000000
$ clang -O1 -mavx fp.c ; ./a.out
-0.000000
Ideally, we'd use IR/node flags to predicate the transform, but the IR parser
doesn't currently allow fast-math-flags on the cast instructions. So for now,
just use the function attribute that corresponds to clang's "-fno-signed-zeros"
option.
Differential Revision: https://reviews.llvm.org/D48085
llvm-svn: 335761
Summary:
The tests in:
https://bugs.llvm.org/show_bug.cgi?id=37751
...show miscompiles because we wrongly mapped and folded x86-specific intrinsics into generic DAG nodes.
This patch corrects the mappings in X86IntrinsicsInfo.h and adds isel matching corresponding to the new patterns. The complete tests for the failure cases should be in avx-cvttp2si.ll and sse-cvttp2si.ll and avx512-cvttp2i.ll
Reviewers: RKSimon, gbedwell, spatel
Reviewed By: spatel
Subscribers: mcrosier, llvm-commits
Differential Revision: https://reviews.llvm.org/D47993
llvm-svn: 334685
We were missing packed isel folding patterns for all of sse41, avx, and avx512.
For some reason avx512 had scalar load folding patterns under optsize(due to partial/undef reg update), but we didn't have the equivalent sse41 and avx patterns.
Sometimes we would get load folding due to peephole pass anyway, but we're also missing avx512 instructions from the load folding table. I'll try to fix that in another patch.
Some of this was spotted in the review for D47993.
This patch adds all the folds to isel, adds a few spot tests, and disables the peephole pass on a few tests to ensure we're testing some of these patterns.
llvm-svn: 334460
Sanjay Patel