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testcase: Add testcase for shrink wrapping of vector<int>::push_back [PR118502]

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LLVM folks noticed that GCC was shrink wrapping the call to vector<int>::push_back.
So I thought it was a good idea to commit a testcase to make sure GCC does not regress
in this area unknowning.

Note the shrink wrapping started with r15-1619-g3b9b8d6cfdf593.
Note this enables the testcase for x86_64 (!ia32), powerpc, aarch64 and riscv which I tested
via godbolt to see the shrink wrapping occurs. Also tested the testcase for both
x86_64-linux-gnu and aarch64-linux-gnu to make sure I got the target selects correct.

Changes since v1:
* v2: Fix some comments typos that was mentioned in the bug report.

	PR rtl-optimization/118502

gcc/testsuite/ChangeLog:

	* g++.dg/opt/shrink-wrapping-vector-1.C: New test.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
This commit is contained in:
Andrew Pinski 2025-01-16 23:47:36 -08:00
parent 992be16d83
commit 33b255a1aa
1 changed files with 17 additions and 0 deletions
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gcc/testsuite/g++.dg/opt/shrink-wrapping-vector-1.C Normal file
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// { dg-do compile { target { { { i?86-*-* x86_64-*-* } && { ! ia32 } } || { powerpc*-*-* aarch64*-*-* riscv*-*-* } } } }
// { dg-options "-O2 -fdump-rtl-pro_and_epilogue" }
// { dg-skip-if "requires hosted libstdc++ for vector" { ! hostedlib } }
// PR rtl-optimization/118502
// The shrink-wrapping should happen around the slow path of vector<int>::push_back,
// The fast path is just checking if there is enough space and doing a few stores.
// We want to verify that shrink wrapping always happens.
#include <vector>
void push_back(std::vector<int>& xs, unsigned char x) {
xs.push_back(x);
}
/* { dg-final { scan-rtl-dump "Performing shrink-wrapping" "pro_and_epilogue" } } */