re PR middle-end/47581 (Unnecessary adjustments to stack pointer)

	PR middle-end/47581
	* config/i386/i386.c (ix86_compute_frame_size): Don't align offset
	if frame size is 0 in a leaf function.

	* gcc.target/i386/pr47581.c: New test.

From-SVN: r170170

gcc/ChangeLog

+2011-02-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/47581
+	* config/i386/i386.c (ix86_compute_frame_size): Don't align offset
+	if frame size is 0 in a leaf function.
+
 2011-02-15  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	PR pch/14940

gcc/config/i386/i386.c

@@ -9307,7 +9307,13 @@ ix86_compute_frame_layout (struct ix86_frame *frame)
   offset += frame->va_arg_size;
 
   /* Align start of frame for local function.  */
-  offset = (offset + stack_alignment_needed - 1) & -stack_alignment_needed;
+  if (stack_realign_fp
+      || offset != frame->sse_reg_save_offset
+      || size != 0
+      || !current_function_is_leaf
+      || cfun->calls_alloca
+      || ix86_current_function_calls_tls_descriptor)
+    offset = (offset + stack_alignment_needed - 1) & -stack_alignment_needed;
 
   /* Frame pointer points here.  */
   frame->frame_pointer_offset = offset;

gcc/testsuite/ChangeLog

+2011-02-15  Jakub Jelinek  <jakub@redhat.com>
+
+	PR middle-end/47581
+	* gcc.target/i386/pr47581.c: New test.
+
 2011-02-14  Janus Weil  <janus@gcc.gnu.org>
 
 	PR fortran/47730

gcc/testsuite/gcc.target/i386/pr47581.c

+/* PR middle-end/47581 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fomit-frame-pointer -mpreferred-stack-boundary=4 -mincoming-stack-boundary=4" } */
+/* { dg-final { scan-assembler-not "(sub|add)l\[\\t \]*\\$\[0-9\]*,\[\\t \]*%\[re\]?sp" } } */
+
+unsigned
+foo (unsigned a, unsigned b)
+{
+  return ((unsigned long long) a * (unsigned long long) b) >> 32;
+}