Patchwork [2/3] Tweek prologues and epilogues for SEH.

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Submitter Richard Henderson
Date Aug. 10, 2010, 9:07 p.m.
Message ID <1281474444-8772-3-git-send-email-rth@redhat.com>
Download mbox | patch
Permalink /patch/61410/
State New
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Comments

Richard Henderson - Aug. 10, 2010, 9:07 p.m.
From: Richard Henderson <rth@twiddle.net>

---
 gcc/config/i386/cygming.h |    3 +++
 gcc/config/i386/i386.c    |   23 +++++++++++++++++++----
 gcc/config/i386/i386.h    |    3 +++
 3 files changed, 25 insertions(+), 4 deletions(-)

Patch

diff --git a/gcc/config/i386/cygming.h b/gcc/config/i386/cygming.h
index a6434f3..4962921 100644
--- a/gcc/config/i386/cygming.h
+++ b/gcc/config/i386/cygming.h
@@ -33,6 +33,9 @@  along with GCC; see the file COPYING3.  If not see
 #define PREFERRED_DEBUGGING_TYPE DBX_DEBUG
 #endif
 
+#undef TARGET_SEH
+#define TARGET_SEH  TARGET_64BIT_MS_ABI
+
 #undef DEFAULT_ABI
 #define DEFAULT_ABI (TARGET_64BIT ? MS_ABI : SYSV_ABI)
 
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 3f37066..938a686 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -9751,6 +9751,11 @@  ix86_expand_prologue (void)
   /* Emit cld instruction if stringops are used in the function.  */
   if (TARGET_CLD && ix86_current_function_needs_cld)
     emit_insn (gen_cld ());
+
+  /* SEH requires that the prologue end within 256 bytes of the start of
+     the function.  Prevent instruction schedules that would extend that.  */
+  if (TARGET_SEH)
+    emit_insn (gen_blockage ());
 }
 
 /* Emit code to restore REG using a POP insn.  */
@@ -9973,13 +9978,16 @@  ix86_expand_epilogue (int style)
   if (crtl->calls_eh_return && style != 2)
     frame.reg_save_offset -= 2 * UNITS_PER_WORD;
 
+  /* EH_RETURN requires the use of moves to function properly.  */
+  if (crtl->calls_eh_return)
+    restore_regs_via_mov = true;
+  /* SEH requires the use of pops to identify the epilogue.  */
+  else if (TARGET_SEH)
+    restore_regs_via_mov = false;
   /* If we're only restoring one register and sp is not valid then
      using a move instruction to restore the register since it's
      less work than reloading sp and popping the register.  */
-  if (!m->fs.sp_valid && frame.nregs <= 1)
-    restore_regs_via_mov = true;
-  /* EH_RETURN requires the use of moves to function properly.  */
-  else if (crtl->calls_eh_return)
+  else if (!m->fs.sp_valid && frame.nregs <= 1)
     restore_regs_via_mov = true;
   else if (TARGET_EPILOGUE_USING_MOVE
 	   && cfun->machine->use_fast_prologue_epilogue
@@ -10090,6 +10098,13 @@  ix86_expand_epilogue (int style)
     }
   else
     {
+      /* SEH requires that the function end with (1) a stack adjustment
+	 if necessary, (2) a sequence of pops, and (3) a return or
+	 jump instruction.  Prevent insns from the function body from
+	 being scheduled into this sequence.  */
+      if (TARGET_SEH)
+	emit_insn (gen_blockage ());
+
       /* First step is to deallocate the stack frame so that we can
 	 pop the registers.  */
       if (!m->fs.sp_valid)
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index a2acc71..eb73df7 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -486,6 +486,9 @@  extern tree x86_mfence;
 /* For the Windows 64-bit ABI.  */
 #define TARGET_64BIT_MS_ABI (TARGET_64BIT && ix86_cfun_abi () == MS_ABI)
 
+/* This is re-defined by cygming.h.  */
+#define TARGET_SEH 0
+
 /* Available call abi.  */
 enum calling_abi
 {