This patch prevents argument promotion of types having
type size greater than 128 bits.
Fixes Bugzilla: https://bugs.llvm.org/show_bug.cgi?id=49952
Details
Details
- Reviewers
nemanjai stefanp - Group Reviewers
Restricted Project - Commits
- rG670736a90474: [PowerPC] Prevent argument promotion of types with size greater than 128 bits
Diff Detail
Diff Detail
- Repository
- rG LLVM Github Monorepo
Event Timeline
| llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp | ||
|---|---|---|
| 1233 | Would it make sense to add some documentation, and perhaps add why we check up to 128 bits? | |
Comment Actions
This will turn off argument promotion for all types wider than 128 bits. An example of a test case that might suffer from worse codegen:
#include <stdio.h>
typedef int __attribute__((vector_size(64))) v8si;
static void __attribute__((noinline)) printWideVec(v8si *ptr) {
v8si WideVec = *ptr;
printf("Vector: { ");
for (int i = 0; i < 7; i++)
printf("%d, ", WideVec[i]);
printf("%d }\n", WideVec[7]);
}
void test(vector signed int a, vector signed int b) {
v8si WideVec = (v8si) { a[0], a[1], a[2], a[3], b[0], b[1], b[2], b[3] };
printWideVec(&WideVec);
}Since we can actually check that the type is <N x i1> for N > 128, we should do that and ensure we are only disabling arg promotion on the MMA types.
| llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp | ||
|---|---|---|
| 1224 | // We need to ensure that argument promotion does not // attempt to promote pointers to MMA types (__vector_pair // and __vector_quad) since these types explicitly cannot be // passed as arguments. Both of these types are larger than // the 128-bit Altivec vectors and have a scalar size of 1 bit. | |
| 1230–1241 | I don't think we need to check the type size in the data layout for this. The primitive type size should be sufficient. This can be simplified to: return llvm::none_of(Args, [](Argument *A) {
auto *EltTy = cast<PointerType>(A->getType())->getElementType();
if (EltTy->isSized())
return (EltTy->isIntOrIntVectorTy(1)) &&
EltTy->getPrimitiveSizeInBits() > 128;
return false;
}); | |
Comment Actions
Also, this is another one we should merge to 12.0.1 so please open the bug, mark it as a blocker and link it here.
Comment Actions
In the previous revision I suggested the following test case:
#include <stdio.h>
typedef int __attribute__((vector_size(64))) v8si;
static void __attribute__((noinline)) printWideVec(v8si *ptr) {
v8si WideVec = *ptr;
printf("Vector: { ");
for (int i = 0; i < 7; i++)
printf("%d, ", WideVec[i]);
printf("%d }\n", WideVec[7]);
}
void test(vector signed int a, vector signed int b) {
v8si WideVec = (v8si) { a[0], a[1], a[2], a[3], b[0], b[1], b[2], b[3] };
printWideVec(&WideVec);
}Can you please add it to this new test case to show that argument promotion is still happening for that case?