On 19-06-14 18:47, Richard Henderson wrote:
And I forgot to mention it might be worth while to notice simple recursion.
Avoid the early exit path if caller == callee, despite the caller-save info not
being valid.
Richard,
attached patch enables handling of self-recursive functions in the
fuse-caller-save optimization, and adds a test-case.
I've done an x86_64 build and ran the i386.exp testsuite.
OK for trunk if full bootstrap and reg-test succeeds?
Thanks,
- Tom
2014-06-26 Tom de Vries <t...@codesourcery.com>
* final.c (get_call_fndecl): Declare.
(self_recursive_call_p): New function.
(collect_fn_hard_reg_usage): Handle self-recursive function calls.
* gcc.target/i386/fuse-caller-save-rec.c: New test.
diff --git a/gcc/final.c b/gcc/final.c
index 9525efc..ed0ba0b 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -225,6 +225,7 @@ static int final_addr_vec_align (rtx);
#endif
static int align_fuzz (rtx, rtx, int, unsigned);
static void collect_fn_hard_reg_usage (void);
+static tree get_call_fndecl (rtx);
/* Initialize data in final at the beginning of a compilation. */
@@ -4750,6 +4751,16 @@ make_pass_clean_state (gcc::context *ctxt)
return new pass_clean_state (ctxt);
}
+/* Return true if INSN is a call to the the current function. */
+
+static bool
+self_recursive_call_p (rtx insn)
+{
+ tree fndecl = get_call_fndecl (insn);
+ return (fndecl == current_function_decl
+ && decl_binds_to_current_def_p (fndecl));
+}
+
/* Collect hard register usage for the current function. */
static void
@@ -4775,7 +4786,8 @@ collect_fn_hard_reg_usage (void)
if (!NONDEBUG_INSN_P (insn))
continue;
- if (CALL_P (insn))
+ if (CALL_P (insn)
+ && !self_recursive_call_p (insn))
{
if (!get_call_reg_set_usage (insn, &insn_used_regs,
call_used_reg_set))
diff --git a/gcc/testsuite/gcc.target/i386/fuse-caller-save-rec.c b/gcc/testsuite/gcc.target/i386/fuse-caller-save-rec.c
new file mode 100644
index 0000000..b30a0b4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/fuse-caller-save-rec.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fuse-caller-save -fomit-frame-pointer -fno-optimize-sibling-calls" } */
+/* { dg-additional-options "-mregparm=1" { target ia32 } } */
+
+/* Test -fuse-caller-save optimization on self-recursive function. */
+
+static int __attribute__((noinline))
+bar (int x)
+{
+ if (x > 4)
+ return bar (x - 3);
+ return 0;
+}
+
+int __attribute__((noinline))
+foo (int y)
+{
+ return y + bar (y);
+}
+
+int
+main (void)
+{
+ return !(foo (5) == 13);
+}
+
+/* Verify that no registers where saved on stack. */
+/* { dg-final { scan-assembler-not "\.cfi_offset" } } */
+
+/* Verify that bar is self-recursive. */
+/* { dg-final { scan-assembler-times "call\tbar" 2 } } */
+
--
1.9.1
