Update preferred stack boundary in ix86_update_stack_boundaryhjl/pr68986/gcc-5-branch

__tls_get_addr must be called with 16-byte aligned stack, which is
guaranted by setting preferred_stack_boundary to 128 bits.  Preferred
stack boundary adjustment for __tls_get_addr should be done in
ix86_update_stack_boundary, not ix86_compute_frame_layout Also
there is no need to over-align stack for __tls_get_addr and function
with __tls_get_addr call isn't a leaf function.

gcc/

	Backport from mainline
	PR target/68986
	* config/i386/i386.c (ix86_compute_frame_layout): Move stack
	alignment adjustment to ...
	(ix86_update_stack_boundary): Here.  Don't over-align stack nor
	change stack_alignment_needed for __tls_get_addr.
	(ix86_finalize_stack_realign_flags): Use stack_alignment_needed
	if __tls_get_addr is called.

gcc/testsuite/

	Backport from mainline
	PR target/68986
	* gcc.target/i386/pr68986-1.c: New test.
	* gcc.target/i386/pr68986-2.c: Likewise.
	* gcc.target/i386/pr68986-3.c: Likewise.

4 files changed, 47 insertions, 16 deletions

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 504e8b8d871..a99d53bfca6 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -10131,18 +10131,6 @@ ix86_compute_frame_layout (struct ix86_frame *frame)
       crtl->preferred_stack_boundary = 128;
       crtl->stack_alignment_needed = 128;
     }
-  /* preferred_stack_boundary is never updated for call
-     expanded from tls descriptor. Update it here. We don't update it in
-     expand stage because according to the comments before
-     ix86_current_function_calls_tls_descriptor, tls calls may be optimized
-     away.  */
-  else if (ix86_current_function_calls_tls_descriptor
-	   && crtl->preferred_stack_boundary < PREFERRED_STACK_BOUNDARY)
-    {
-      crtl->preferred_stack_boundary = PREFERRED_STACK_BOUNDARY;
-      if (crtl->stack_alignment_needed < PREFERRED_STACK_BOUNDARY)
-	crtl->stack_alignment_needed = PREFERRED_STACK_BOUNDARY;
-    }
 
   stack_alignment_needed = crtl->stack_alignment_needed / BITS_PER_UNIT;
   preferred_alignment = crtl->preferred_stack_boundary / BITS_PER_UNIT;
@@ -10816,6 +10804,11 @@ ix86_update_stack_boundary (void)
       && cfun->stdarg
       && crtl->stack_alignment_estimated < 128)
     crtl->stack_alignment_estimated = 128;
+
+  /* __tls_get_addr needs to be called with 16-byte aligned stack.  */
+  if (ix86_tls_descriptor_calls_expanded_in_cfun
+      && crtl->preferred_stack_boundary < 128)
+    crtl->preferred_stack_boundary = 128;
 }
 
 /* Handle the TARGET_GET_DRAP_RTX hook.  Return NULL if no DRAP is
@@ -11275,10 +11268,11 @@ ix86_finalize_stack_realign_flags (void)
   unsigned int incoming_stack_boundary
     = (crtl->parm_stack_boundary > ix86_incoming_stack_boundary
        ? crtl->parm_stack_boundary : ix86_incoming_stack_boundary);
-  unsigned int stack_realign = (incoming_stack_boundary
-				< (crtl->is_leaf
-				   ? crtl->max_used_stack_slot_alignment
-				   : crtl->stack_alignment_needed));
+  unsigned int stack_realign
+    = (incoming_stack_boundary
+       < (crtl->is_leaf && !ix86_current_function_calls_tls_descriptor
+	  ? crtl->max_used_stack_slot_alignment
+	  : crtl->stack_alignment_needed));
 
   if (crtl->stack_realign_finalized)
     {
diff --git a/gcc/testsuite/gcc.target/i386/pr68986-1.c b/gcc/testsuite/gcc.target/i386/pr68986-1.c
new file mode 100644
index 00000000000..998f34f05b4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68986-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target tls_native } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-fPIC -mno-accumulate-outgoing-args -mpreferred-stack-boundary=5 -mincoming-stack-boundary=4" } */
+
+extern __thread int msgdata;
+int
+foo ()
+{
+  return msgdata;
+}
diff --git a/gcc/testsuite/gcc.target/i386/pr68986-2.c b/gcc/testsuite/gcc.target/i386/pr68986-2.c
new file mode 100644
index 00000000000..c3a366c1958
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68986-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile { target ia32 } } */
+/* { dg-require-effective-target tls_native } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-fPIC -mno-accumulate-outgoing-args -mpreferred-stack-boundary=2" } */
+
+extern __thread int msgdata;
+int
+foo ()
+{
+  return msgdata;
+}
+
+/* { dg-final { scan-assembler "andl\[\\t \]*\\$-16,\[\\t \]*%esp" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr68986-3.c b/gcc/testsuite/gcc.target/i386/pr68986-3.c
new file mode 100644
index 00000000000..5744cf222ae
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr68986-3.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target tls_native } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-fPIC -mno-sse -mpreferred-stack-boundary=3 -mincoming-stack-boundary=3" } */
+
+extern __thread int msgdata;
+int
+foo ()
+{
+  return msgdata;
+}
+
+/* { dg-final { scan-assembler "and\[lq\]\[\\t \]*\\$-16,\[\\t \]*%\[re\]?sp" } } */