https://gcc.gnu.org/g:3b9b8d6cfdf59337f4b7ce10ce92a98044b2657b
commit r15-1619-g3b9b8d6cfdf59337f4b7ce10ce92a98044b2657b
Author: Surya Kumari Jangala <jskum...@linux.ibm.com>
Date: Tue Jun 25 08:37:49 2024 -0500
ira: Scale save/restore costs of callee save registers with block frequency
In assign_hard_reg(), when computing the costs of the hard registers, the
cost of saving/restoring a callee-save hard register in prolog/epilog is
taken into consideration. However, this cost is not scaled with the entry
block frequency. Without scaling, the cost of saving/restoring is quite
small and this can result in a callee-save register being chosen by
assign_hard_reg() even though there are free caller-save registers
available. Assigning a callee save register to a pseudo that is live
in the entire function and across a call will cause shrink wrap to fail.
2024-06-25 Surya Kumari Jangala <jskum...@linux.ibm.com>
gcc/
PR rtl-optimization/111673
* ira-color.cc (assign_hard_reg): Scale save/restore costs of
callee save registers with block frequency.
gcc/testsuite/
PR rtl-optimization/111673
* gcc.target/powerpc/pr111673.c: New test.
Diff:
---
gcc/ira-color.cc | 4 +++-
gcc/testsuite/gcc.target/powerpc/pr111673.c | 17 +++++++++++++++++
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
index b9ae32d1b4d..ca32a23a0c9 100644
--- a/gcc/ira-color.cc
+++ b/gcc/ira-color.cc
@@ -2178,7 +2178,9 @@ assign_hard_reg (ira_allocno_t a, bool retry_p)
add_cost = ((ira_memory_move_cost[mode][rclass][0]
+ ira_memory_move_cost[mode][rclass][1])
* saved_nregs / hard_regno_nregs (hard_regno,
- mode) - 1);
+ mode) - 1)
+ * (optimize_size ? 1 :
+ REG_FREQ_FROM_BB (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
cost += add_cost;
full_cost += add_cost;
}
diff --git a/gcc/testsuite/gcc.target/powerpc/pr111673.c
b/gcc/testsuite/gcc.target/powerpc/pr111673.c
new file mode 100644
index 00000000000..e0c0f85460a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr111673.c
@@ -0,0 +1,17 @@
+/* { dg-do compile { target lp64 } } */
+/* { dg-options "-O2 -fdump-rtl-pro_and_epilogue" } */
+
+/* Verify there is an early return without the prolog and shrink-wrap
+ the function. */
+
+int f (int);
+int
+advance (int dz)
+{
+ if (dz > 0)
+ return (dz + dz) * dz;
+ else
+ return dz * f (dz);
+}
+
+/* { dg-final { scan-rtl-dump-times "Performing shrink-wrapping" 1
"pro_and_epilogue" } } */
