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[1/3,i386] Move stack frame re-alignment to before SSE saves.

Message ID 20161222205825.21319-1-daniel.santos@pobox.com
State New
Headers show

Commit Message

Daniel Santos Dec. 22, 2016, 8:58 p.m. UTC 
This step adds new fields to struct ix86_frame to track where we started
the stack re-alignment and what we need to allocate prior to
re-alignment.  In ix86_compute_frame_layout, we do the stack frame
re-alignment computation prior to computing the SSE save area so that it
we have an aligned SSE save area.

This new also assures that the SSE save area is properly aligned when
DRAP is used.
---
 gcc/config/i386/i386.c | 40 +++++++++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 15 deletions(-)
diff mbox

Patch

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 792e8ec232d..7f7389cbe31 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -2453,7 +2453,7 @@  struct GTY(()) stack_local_entry {
    [saved regs]
 					<- regs_save_offset
    [padding0]
-
+					<- stack_realign_offset
    [saved SSE regs]
 					<- sse_regs_save_offset
    [padding1]          |
@@ -2479,6 +2479,8 @@  struct ix86_frame
   HOST_WIDE_INT stack_pointer_offset;
   HOST_WIDE_INT hfp_save_offset;
   HOST_WIDE_INT reg_save_offset;
+  HOST_WIDE_INT stack_realign_allocate_offset;
+  HOST_WIDE_INT stack_realign_offset;
   HOST_WIDE_INT sse_reg_save_offset;
 
   /* When save_regs_using_mov is set, emit prologue using
@@ -12457,28 +12459,36 @@  ix86_compute_frame_layout (struct ix86_frame *frame)
   if (TARGET_SEH)
     frame->hard_frame_pointer_offset = offset;
 
+  /* When re-aligning the stack frame, but not saving SSE registers, this
+     is the offset we want to allocate memory for.  */
+  frame->stack_realign_allocate_offset = offset;
+
+  /* The re-aligned stack starts here.  Values before this point are not
+     directly comparable with values below this point.  Use sp_valid_at
+     to determine if the stack pointer is valid for a given offset and
+     fp_valid_at for the frame pointer.  */
+  if (stack_realign_fp)
+    offset = ROUND_UP (offset, stack_alignment_needed);
+  frame->stack_realign_offset = offset;
+
   /* Align and set SSE register save area.  */
   if (frame->nsseregs)
     {
       /* The only ABI that has saved SSE registers (Win64) also has a
-	 16-byte aligned default stack, and thus we don't need to be
-	 within the re-aligned local stack frame to save them.  In case
-	 incoming stack boundary is aligned to less than 16 bytes,
-	 unaligned move of SSE register will be emitted, so there is
-	 no point to round up the SSE register save area outside the
-	 re-aligned local stack frame to 16 bytes.  */
-      if (ix86_incoming_stack_boundary >= 128)
+	 16-byte aligned default stack.  However, many programs violate
+	 the ABI, and Wine64 forces stack realignment to compensate.
+
+	 If the incoming stack boundary is at least 16 bytes, or DRAP is
+	 required and the DRAP re-alignment boundary is at least 16 bytes,
+	 then we want the SSE register save area properly aligned.  */
+      if (ix86_incoming_stack_boundary >= 128
+	       || (stack_realign_drap && stack_alignment_needed >= 16))
 	offset = ROUND_UP (offset, 16);
       offset += frame->nsseregs * 16;
+      frame->stack_realign_allocate_offset = offset;
     }
-  frame->sse_reg_save_offset = offset;
 
-  /* The re-aligned stack starts here.  Values before this point are not
-     directly comparable with values below this point.  In order to make
-     sure that no value happens to be the same before and after, force
-     the alignment computation below to add a non-zero value.  */
-  if (stack_realign_fp)
-    offset = ROUND_UP (offset, stack_alignment_needed);
+  frame->sse_reg_save_offset = offset;
 
   /* Va-arg area */
   frame->va_arg_size = ix86_varargs_gpr_size + ix86_varargs_fpr_size;