re PR target/39118 (x86_64 red zone violation)

	PR target/39118
	* config/i386/i386.md (UNSPEC_MEMORY_BLOCKAGE): New constant.
	(memory_blockage): New expander.
	(*memory_blockage): New insn pattern.
	* config/i386/i386.c (ix86_expand_prologue): Use memory_blockage
	instead of general blockage at the end of function prologue when
	frame pointer is used to access red zone area.  Do not emit blockage
	when profiling, it is emitted in generic code.
	(ix86_expand_epilogue): Emit memory_blockage at the beginning of
	function epilogue when frame pointer is used to access red zone area.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>
From-SVN: r144101

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 944c0e9cf7cb7d8e2c508f4376d225ab2766d942..779b481729b2d1e4ff8acc5430bce836cc826254 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,17 @@
+2009-02-11  Uros Bizjak  <ubizjak@gmail.com>
+           Jakub Jelinek  <jakub@redhat.com>
+
+       PR target/39118
+       * config/i386/i386.md (UNSPEC_MEMORY_BLOCKAGE): New constant.
+       (memory_blockage): New expander.
+       (*memory_blockage): New insn pattern.
+       * config/i386/i386.c (ix86_expand_prologue): Use memory_blockage
+       instead of general blockage at the end of function prologue when
+       frame pointer is used to access red zone area.  Do not emit blockage
+       when profiling, it is emitted in generic code.
+       (ix86_expand_epilogue): Emit memory_blockage at the beginning of
+       function epilogue when frame pointer is used to access red zone area.
+
 2009-02-10  Steve Ellcey  <sje@cup.hp.com>
 
        PR c/39084

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index b1569f8fe5ec032e7d4c7664c1c78b7218772293..ff7b52fd8fbb558b48103cc71806ad021c3b4934 100644 (file)
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -6304,7 +6304,6 @@ ix86_expand_prologue (void)
 {
   rtx insn;
   bool pic_reg_used;
-  bool emit_blockage = false;
   struct ix86_frame frame;
   HOST_WIDE_INT allocate;
 
@@ -6484,14 +6483,12 @@ ix86_expand_prologue (void)
         insn = emit_insn (gen_set_got (pic_offset_table_rtx));
     }
 
-  /* Prevent function calls from being scheduled before the call to mcount.
-     In the pic_reg_used case, make sure that the got load isn't deleted.  */
-  if (current_function_profile)
-    {
-      if (pic_reg_used)
-       emit_insn (gen_prologue_use (pic_offset_table_rtx));
-      emit_blockage = true;
-    }
+  /* In the pic_reg_used case, make sure that the got load isn't deleted
+     when mcount needs it.  Blockage to avoid call movement across mcount
+     call is emitted in generic code after the NOTE_INSN_PROLOGUE_END
+     note.  */
+  if (current_function_profile && pic_reg_used)
+    emit_insn (gen_prologue_use (pic_offset_table_rtx));
 
   /* Prevent instructions from being scheduled into register save push
      sequence when access to the redzone area is done through frame pointer.
@@ -6500,10 +6497,7 @@ ix86_expand_prologue (void)
      prologue, and moving instructions that access redzone area via frame
      pointer inside push sequence violates this assumption.  */
   if (frame_pointer_needed && frame.red_zone_size)
-    emit_blockage = true;
-
-  if (emit_blockage)
-    emit_insn (gen_blockage ());
+    emit_insn (gen_memory_blockage ());
 
   /* Emit cld instruction if stringops are used in the function.  */
   if (TARGET_CLD && ix86_current_function_needs_cld)
@@ -6552,6 +6546,11 @@ ix86_expand_epilogue (int style)
 
   ix86_compute_frame_layout (&frame);
 
+  /* See the comment about red zone and frame
+     pointer usage in ix86_expand_prologue.  */
+  if (frame_pointer_needed && frame.red_zone_size)
+    emit_insn (gen_memory_blockage ()); 
+
   /* Calculate start of saved registers relative to ebp.  Special care
      must be taken for the normal return case of a function using
      eh_return: the eax and edx registers are marked as saved, but not

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index e304541eaf9774f48a8e4010c60f3cdad686adce..2487eb92392b131ec63b85a266dd73284e17615d 100644 (file)
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -67,12 +67,13 @@
    (UNSPEC_DEF_CFA             15)
    (UNSPEC_SET_RIP             16)
    (UNSPEC_SET_GOT_OFFSET      17)
+   (UNSPEC_MEMORY_BLOCKAGE     18)
 
    ; TLS support
-   (UNSPEC_TP                  18)
-   (UNSPEC_TLS_GD              19)
-   (UNSPEC_TLS_LD_BASE         20)
-   (UNSPEC_TLSDESC             21)
+   (UNSPEC_TP                  20)
+   (UNSPEC_TLS_GD              21)
+   (UNSPEC_TLS_LD_BASE         22)
+   (UNSPEC_TLSDESC             23)
 
    ; Other random patterns
    (UNSPEC_SCAS                        30)
@@ -14877,6 +14878,24 @@
   ""
   [(set_attr "length" "0")])
 
+;; Do not schedule instructions accessing memory across this point.
+
+(define_expand "memory_blockage"
+  [(set (match_dup 0)
+       (unspec:BLK [(match_dup 0)] UNSPEC_MEMORY_BLOCKAGE))]
+  ""
+{
+  operands[0] = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (Pmode));
+  MEM_VOLATILE_P (operands[0]) = 1;
+})
+
+(define_insn "*memory_blockage"
+  [(set (match_operand:BLK 0 "" "")
+       (unspec:BLK [(match_dup 0)] UNSPEC_MEMORY_BLOCKAGE))]
+  ""
+  ""
+  [(set_attr "length" "0")])
+
 ;; As USE insns aren't meaningful after reload, this is used instead
 ;; to prevent deleting instructions setting registers for PIC code
 (define_insn "prologue_use"