[PATCH 2/2] [i386] PR82002 Part 2: Correct non-immediate offset/invalid INSN

[Daniel Santos <daniel dot santos at pobox dot com>]

When we are realigning the stack pointer, making an ms_abi to sysv_abi
call and alllocating 2GiB or more on the stack we end up with an invalid
INSN due to a non-immediate offset.  This occurs both with and without
-mcall-ms2sysv-xlogues.  Additionally, I've discovered that the stack
allocation with -mcall-ms2sysv-xlogues is incorrect as it ignores stack
checking, stack clash checking and probing.

This patch fixes these problems by

1. No longer allocate stack space in ix86_emit_outlined_ms2sysv_save.
2. Rearrange where we emit SSE saves or stub call:
   a. Before frame allocation when offset from frame to save area is >= 2GiB.
   b. After frame allocation when frame is < 2GiB.  (Stack allocations
      prior to the stub call can't be combined with those afterwards, so
      this is better when possible.)
3. Modify choose_baseaddr to take an optional scratch_regno argument
   and never return rtx that cannot be used as an immediate.

gcc:
	config/i386/i386.c (choose_basereg): Use optional scratch
	register and add assertion.
	(x86_emit_outlined_ms2sysv_save): use scratch register when
	needed, and don't allocate stack.
	(ix86_expand_prologue): Rearrange where SSE saves/stub call is
	emitted, correct wrong allocation with -mcall-ms2sysv-xlogues.
	(ix86_emit_outlined_ms2sysv_restore): Fix non-immediate offsets.

gcc/testsuite:
	gcc.target/i386/pr82002-2a.c: Change from xfail to fail.
	gcc.target/i386/pr82002-2b.c: Likewise.

Signed-off-by: Daniel Santos <daniel.santos@pobox.com>
---
 gcc/config/i386/i386.c                     | 76 ++++++++++++++++++++++++------
 gcc/testsuite/gcc.target/i386/pr82002-2a.c |  2 -
 gcc/testsuite/gcc.target/i386/pr82002-2b.c |  2 -
 3 files changed, 62 insertions(+), 18 deletions(-)

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 83a07afb3e1..abd8e937e0d 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -11520,7 +11520,8 @@ choose_basereg (HOST_WIDE_INT cfa_offset, rtx &base_reg,
    The valid base registers are taken from CFUN->MACHINE->FS.  */
 
 static rtx
-choose_baseaddr (HOST_WIDE_INT cfa_offset, unsigned int *align)
+choose_baseaddr (HOST_WIDE_INT cfa_offset, unsigned int *align,
+		 int scratch_regno = -1)
 {
   rtx base_reg = NULL;
   HOST_WIDE_INT base_offset = 0;
@@ -11534,6 +11535,28 @@ choose_baseaddr (HOST_WIDE_INT cfa_offset, unsigned int *align)
     choose_basereg (cfa_offset, base_reg, base_offset, 0, align);
 
   gcc_assert (base_reg != NULL);
+
+  if (TARGET_64BIT)
+    {
+      rtx base_offset_rtx = GEN_INT (base_offset);
+
+      if (scratch_regno >= 0)
+	{
+	  if (!x86_64_immediate_operand (base_offset_rtx, DImode))
+	    {
+	      rtx tmp;
+	      rtx scratch_reg = gen_rtx_REG (DImode, scratch_regno);
+
+	      emit_insn (gen_rtx_SET (scratch_reg, base_offset_rtx));
+	      tmp = gen_rtx_PLUS (DImode, scratch_reg, base_reg);
+	      emit_insn (gen_rtx_SET (scratch_reg, tmp));
+	      return scratch_reg;
+	    }
+	}
+      else
+	gcc_assert (x86_64_immediate_operand (base_offset_rtx, DImode));
+    }
+
   return plus_constant (Pmode, base_reg, base_offset);
 }
 
@@ -12793,23 +12816,22 @@ ix86_emit_outlined_ms2sysv_save (const struct ix86_frame &frame)
   rtx sym, addr;
   rtx rax = gen_rtx_REG (word_mode, AX_REG);
   const struct xlogue_layout &xlogue = xlogue_layout::get_instance ();
-  HOST_WIDE_INT allocate = frame.stack_pointer_offset - m->fs.sp_offset;
 
   /* AL should only be live with sysv_abi.  */
   gcc_assert (!ix86_eax_live_at_start_p ());
+  gcc_assert (m->fs.sp_offset >= frame.sse_reg_save_offset);
 
   /* Setup RAX as the stub's base pointer.  We use stack_realign_offset rather
      we've actually realigned the stack or not.  */
   align = GET_MODE_ALIGNMENT (V4SFmode);
   addr = choose_baseaddr (frame.stack_realign_offset
-			  + xlogue.get_stub_ptr_offset (), &align);
+			  + xlogue.get_stub_ptr_offset (), &align, AX_REG);
   gcc_assert (align >= GET_MODE_ALIGNMENT (V4SFmode));
-  emit_insn (gen_rtx_SET (rax, addr));
 
-  /* Allocate stack if not already done.  */
-  if (allocate > 0)
-      pro_epilogue_adjust_stack (stack_pointer_rtx, stack_pointer_rtx,
-				GEN_INT (-allocate), -1, false);
+  /* If choose_baseaddr returned our scratch register, then we don't need to
+     do another SET.  */
+  if (!REG_P (addr) || REGNO (addr) != AX_REG)
+    emit_insn (gen_rtx_SET (rax, addr));
 
   /* Get the stub symbol.  */
   sym = xlogue.get_stub_rtx (frame_pointer_needed ? XLOGUE_STUB_SAVE_HFP
@@ -12841,6 +12863,7 @@ ix86_expand_prologue (void)
   HOST_WIDE_INT allocate;
   bool int_registers_saved;
   bool sse_registers_saved;
+  bool save_stub_call_needed;
   rtx static_chain = NULL_RTX;
 
   if (ix86_function_naked (current_function_decl))
@@ -13016,6 +13039,8 @@ ix86_expand_prologue (void)
 
   int_registers_saved = (frame.nregs == 0);
   sse_registers_saved = (frame.nsseregs == 0);
+  save_stub_call_needed = (m->call_ms2sysv);
+  gcc_assert (!(!sse_registers_saved && save_stub_call_needed));
 
   if (frame_pointer_needed && !m->fs.fp_valid)
     {
@@ -13110,10 +13135,27 @@ ix86_expand_prologue (void)
 	 target.  */
       if (TARGET_SEH)
 	m->fs.sp_valid = false;
-    }
 
-  if (m->call_ms2sysv)
-    ix86_emit_outlined_ms2sysv_save (frame);
+      /* If SP offset is non-immediate after allocation of the stack frame,
+	 then emit SSE saves or stub call prior to allocating the rest of the
+	 stack frame.  This is less efficient for the out-of-line stub because
+	 we can't combine allocations across the call barrier, but it's better
+	 than using a scratch register.  */
+      else if (frame.stack_pointer_offset - m->fs.sp_realigned_offset
+	       > 0x7fffffff)
+	{
+	  if (!sse_registers_saved)
+	    {
+	      ix86_emit_save_sse_regs_using_mov (frame.sse_reg_save_offset);
+	      sse_registers_saved = true;
+	    }
+	  else if (save_stub_call_needed)
+	    {
+	      ix86_emit_outlined_ms2sysv_save (frame);
+	      save_stub_call_needed = false;
+	    }
+	}
+    }
 
   allocate = frame.stack_pointer_offset - m->fs.sp_offset;
 
@@ -13337,6 +13379,8 @@ ix86_expand_prologue (void)
     ix86_emit_save_regs_using_mov (frame.reg_save_offset);
   if (!sse_registers_saved)
     ix86_emit_save_sse_regs_using_mov (frame.sse_reg_save_offset);
+  else if (save_stub_call_needed)
+    ix86_emit_outlined_ms2sysv_save (frame);
 
   /* For the mcount profiling on 32 bit PIC mode we need to emit SET_GOT
      in PROLOGUE.  */
@@ -13560,7 +13604,7 @@ ix86_emit_outlined_ms2sysv_restore (const struct ix86_frame &frame,
   rtvec v;
   unsigned int elems_needed, align, i, vi = 0;
   rtx_insn *insn;
-  rtx sym, tmp;
+  rtx sym, addr, tmp;
   rtx rsi = gen_rtx_REG (word_mode, SI_REG);
   rtx r10 = NULL_RTX;
   const struct xlogue_layout &xlogue = xlogue_layout::get_instance ();
@@ -13577,9 +13621,13 @@ ix86_emit_outlined_ms2sysv_restore (const struct ix86_frame &frame,
 
   /* Setup RSI as the stub's base pointer.  */
   align = GET_MODE_ALIGNMENT (V4SFmode);
-  tmp = choose_baseaddr (rsi_offset, &align);
+  addr = choose_baseaddr (rsi_offset, &align, SI_REG);
   gcc_assert (align >= GET_MODE_ALIGNMENT (V4SFmode));
-  emit_insn (gen_rtx_SET (rsi, tmp));
+
+  /* If choose_baseaddr returned our scratch register, then we don't need to
+     do another SET.  */
+  if (!REG_P (addr) || REGNO (addr) != SI_REG)
+    emit_insn (gen_rtx_SET (rsi, addr));
 
   /* Get a symbol for the stub.  */
   if (frame_pointer_needed)
diff --git a/gcc/testsuite/gcc.target/i386/pr82002-2a.c b/gcc/testsuite/gcc.target/i386/pr82002-2a.c
index bc85080ba8e..c31440debe2 100644
--- a/gcc/testsuite/gcc.target/i386/pr82002-2a.c
+++ b/gcc/testsuite/gcc.target/i386/pr82002-2a.c
@@ -1,7 +1,5 @@
 /* { dg-do compile { target lp64 } } */
 /* { dg-options "-Ofast -mstackrealign -mabi=ms" } */
-/* { dg-xfail-if "" { *-*-* }  } */
-/* { dg-xfail-run-if "" { *-*-* }  } */
 
 void __attribute__((sysv_abi)) a (char *);
 void
diff --git a/gcc/testsuite/gcc.target/i386/pr82002-2b.c b/gcc/testsuite/gcc.target/i386/pr82002-2b.c
index 10e44cd7b1d..939e069517d 100644
--- a/gcc/testsuite/gcc.target/i386/pr82002-2b.c
+++ b/gcc/testsuite/gcc.target/i386/pr82002-2b.c
@@ -1,7 +1,5 @@
 /* { dg-do compile { target lp64 } } */
 /* { dg-options "-Ofast -mstackrealign -mabi=ms -mcall-ms2sysv-xlogues" } */
-/* { dg-xfail-if "" { *-*-* }  } */
-/* { dg-xfail-run-if "" { *-*-* }  } */
 
 void __attribute__((sysv_abi)) a (char *);
 void
-- 
2.14.3