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.
(cherry picked from commit
3e16b4359e86b36676ed01219e6deafa95f3c16b)
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;
--- /dev/null
+/* { dg-options "-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;
+}