Re: [PATCH] Add -Wdisabled-optimization warning for not optimizing sibling calls

[Bradley Lucier <lucier@purdue.edu>]

On 8/5/23 5:53 PM, David Malcolm wrote:
> ...but the warning branch uses "warning", which implicitly uses the
> input_location global variable.  Is the warning reported at the correct
> place?  It's better to use warning_at and pass it the location at which
> the warning should be emitted.

Thanks, I changed the patch to follow your suggestion.

I built and ran make check with the patch; there were no changes to the 
test results.

As a test, I again built GCC with

../../gcc-mainline/configure CXX="/pkgs/gcc-mainline-new-new/bin/g++ 
-Wdisabled-optimization" --enable-languages=c --disable-multilib 
--prefix=/pkgs/gcc-mainline-test-test --disable-werror --disable-bootstrap

I found no changes to the warning messages.

Brad

diff --git a/gcc/calls.cc b/gcc/calls.cc
index 1f3a6d5c450..de293ac51bb 100644
--- a/gcc/calls.cc
+++ b/gcc/calls.cc
@@ -1242,10 +1242,12 @@ void
  maybe_complain_about_tail_call (tree call_expr, const char *reason)
  {
    gcc_assert (TREE_CODE (call_expr) == CALL_EXPR);
-  if (!CALL_EXPR_MUST_TAIL_CALL (call_expr))
-    return;
-
-  error_at (EXPR_LOCATION (call_expr), "cannot tail-call: %s", reason);
+  if (CALL_EXPR_MUST_TAIL_CALL (call_expr))
+    error_at (EXPR_LOCATION (call_expr), "cannot tail-call: %s", reason);
+  else if (flag_optimize_sibling_calls)
+    warning_at (EXPR_LOCATION (call_expr), OPT_Wdisabled_optimization,
+                "cannot apply sibling-call optimization: %s", reason);
+  return;
  }

  /* Fill in ARGS_SIZE and ARGS array based on the parameters found in