[PATCH] ifcvt, m68k: Handle targets without scheduling models

[wangjue]

From: juewang <juew...@linux.alibaba.com>

m68k_sched_issue_rate can be called for targets without a scheduling
model.  Return 1 for those targets instead of calling gcc_unreachable.

Add tests for if-conversion costing on single-issue and multi-issue
targets.

Assisted-by: Codex (OpenAI)

gcc/ChangeLog:

        * config/m68k/m68k.cc (m68k_sched_issue_rate): Return one for CPUs
        without a scheduling model.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/ifcvt-parallel-cost-1.c: New test.
        * gcc.target/riscv/ifcvt-parallel-cost-2.c: Likewise.
---
 gcc/config/m68k/m68k.cc                       |  3 +-
 .../gcc.target/riscv/ifcvt-parallel-cost-1.c  | 26 +++++++++++++++++
 .../gcc.target/riscv/ifcvt-parallel-cost-2.c  | 29 +++++++++++++++++++
 3 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-1.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-2.c

diff --git a/gcc/config/m68k/m68k.cc b/gcc/config/m68k/m68k.cc
index b6134892883..074d82efb25 100644
--- a/gcc/config/m68k/m68k.cc
+++ b/gcc/config/m68k/m68k.cc
@@ -6594,8 +6594,7 @@ m68k_sched_issue_rate (void)
       return 2;
 
     default:
-      gcc_unreachable ();
-      return 0;
+      return 1;
     }
 }
 
diff --git a/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-1.c 
b/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-1.c
new file mode 100644
index 00000000000..1bec3f77dcd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-1.c
@@ -0,0 +1,26 @@
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-Os" "-Oz" } } */
+/* { dg-options "-O2 -march=rv64gc_zicond -mabi=lp64d -mtune=xt-c9501fdvt 
-mbranch-cost=3" } */
+
+extern void consume (void *, void *, void *);
+
+__attribute__ ((noinline, noclone))
+void
+select_three_pointers (long x, long y,
+                      void *a0, void *a1,
+                      void *b0, void *b1,
+                      void *c0, void *c1)
+{
+  if (x > y)
+    {
+      a0 = a1;
+      b0 = b1;
+      c0 = c1;
+    }
+
+  consume (a0, b0, c0);
+}
+
+/* { dg-final { scan-assembler-times "\\sczero\\.eqz\\s" 3 } } */
+/* { dg-final { scan-assembler-times "\\sczero\\.nez\\s" 3 } } */
+/* { dg-final { scan-assembler-not "\\s(?:bge|bgt|ble|blt)\\s" } } */
diff --git a/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-2.c 
b/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-2.c
new file mode 100644
index 00000000000..6e1f9ed7849
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/ifcvt-parallel-cost-2.c
@@ -0,0 +1,29 @@
+/* { dg-do compile } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-Os" "-Oz" } } */
+/* { dg-options "-O2 -march=rv64gc_zicond -mabi=lp64d -mtune=generic 
-mbranch-cost=3" } */
+
+extern void consume (void *, void *, void *);
+
+__attribute__ ((noinline, noclone))
+void
+select_three_pointers_generic (long x, long y,
+                              void *a0, void *a1,
+                              void *b0, void *b1,
+                              void *c0, void *c1)
+{
+  if (x >= y)
+    {
+      a0 = a1;
+      b0 = b1;
+      c0 = c1;
+    }
+
+  consume (a0, b0, c0);
+}
+
+/* The generic tuning model has an issue rate of one, so the three pointer
+   selections are not profitable at a branch cost of three.  */
+
+/* { dg-final { scan-assembler-times "\\sbge\\s" 1 } } */
+/* { dg-final { scan-assembler-not "\\sczero\\.eqz\\s" } } */
+/* { dg-final { scan-assembler-not "\\sczero\\.nez\\s" } } */
-- 
2.34.1