From: Surya Kumari Jangala <jskumari@linux.vnet.ibm.com>
To: gcc-patches@gcc.gnu.org, bergner@linux.ibm.com,
segher@kernel.crashing.org
Subject: [PATCH] regrename: Fix -fcompare-debug issue in check_new_reg_p [PR105041]
Date: Fri, 10 Jun 2022 19:52:57 +0530 [thread overview]
Message-ID: <272d6c10-b6eb-a656-1a7c-b071c138b0ed@linux.vnet.ibm.com> (raw)
regrename: Fix -fcompare-debug issue in check_new_reg_p [PR105041]
In check_new_reg_p, the nregs of a du chain is computed by obtaining the MODE
of the first element in the chain, and then calling hard_regno_nregs() with the
MODE. But the first element of the chain can be a DEBUG_INSN whose mode need
not be the same as the rest of the elements in the du chain. This
was resulting in fcompare-debug failure as check_new_reg_p was returning a
different result with -g for the same candidate register. We can instead obtain
nregs from the du chain itself.
2022-06-10 Surya Kumari Jangala <jskumari@linux.ibm.com>
gcc/
PR rtl-optimization/105041
* regrename.cc (check_new_reg_p): Use nregs value from du chain.
gcc/testsuite/
PR rtl-optimization/105041
* gcc.target/powerpc/pr105041.c: New test.
diff --git a/gcc/regrename.cc b/gcc/regrename.cc
index 10271e1..f651351 100644
--- a/gcc/regrename.cc
+++ b/gcc/regrename.cc
@@ -324,8 +324,7 @@ static bool
check_new_reg_p (int reg ATTRIBUTE_UNUSED, int new_reg,
class du_head *this_head, HARD_REG_SET this_unavailable)
{
- machine_mode mode = GET_MODE (*this_head->first->loc);
- int nregs = hard_regno_nregs (new_reg, mode);
+ int nregs = this_head->nregs;
int i;
struct du_chain *tmp;
diff --git a/gcc/testsuite/gcc.target/powerpc/pr105041.c b/gcc/testsuite/gcc.target/powerpc/pr105041.c
new file mode 100644
index 0000000..89eed1c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr105041.c
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target be } */
+/* { dg-options "-m32 -mdejagnu-cpu=power4 -O2 -fcompare-debug -fharden-compares -frename-registers" } */
+
+double m;
+int n;
+
+unsigned int
+foo (unsigned int x, int y)
+{
+ long long int a = y, b = !a;
+ int c = 0;
+
+ if (b != x)
+ while ((int) m == a)
+ {
+ c = a;
+ a = 0;
+ }
+
+ n = b = y;
+
+ return x + c;
+}
next reply other threads:[~2022-06-10 14:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-10 14:22 Surya Kumari Jangala [this message]
2022-06-10 15:40 ` Segher Boessenkool
2022-06-10 20:09 ` Jeff Law
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