> I tried to figure out why things had been done in this
> slightly convoluted manner and failed. It seems to me that
> this is easily represented with the individual instructions.
> A comment indicated that there had been problems with the
> copy to %o7 being deleted. Elsewhere we have successfully
> used a naked USE pattern to keep such things from being
> deleted.
I have 4 regressions in the C testsuite with -mflat on SPARC/Solaris:
FAIL: gcc.c-torture/execute/builtins/stpcpy-chk.c execution, -O2 -flto
FAIL: gcc.c-torture/execute/nestfunc-4.c execution, -Os
FAIL: gcc.c-torture/execute/pr19005.c execution, -O2
FAIL: gcc.c-torture/execute/strncmp-1.c execution, -O2 -flt
The problem is that the blockage isn't emitted if the frame pointer isn't used.
I have also fixed the swapping %o7/%i7 (despite the name, %o7 is the incoming
return address register from GCC's viewpoint, and %i7 the register where you
save the return address for the rest of the function).
Tested on SPARC/Solaris, applied on the mainline.
2011-06-26 Eric Botcazou <ebotca...@adacore.com>
* config/sparc/sparc.c (save_local_or_in_reg_p): Adjust comment.
(emit_save_register_window): Likewise.
(sparc_expand_prologue): Use SIZE_INT_RTX and SIZE_RTX variables.
(sparc_flat_expand_prologue): Add comment. Always emit blockage.
Swap back %o7/%i7 in register naming.
--
Eric Botcazou
Index: config/sparc/sparc.c
===================================================================
--- config/sparc/sparc.c (revision 175398)
+++ config/sparc/sparc.c (working copy)
@@ -4149,7 +4149,7 @@ save_local_or_in_reg_p (unsigned int reg
if (regno == RETURN_ADDR_REGNUM && return_addr_reg_needed_p (leaf_function))
return true;
- /* PIC register (%l7) if needed. */
+ /* GOT register (%l7) if needed. */
if (regno == PIC_OFFSET_TABLE_REGNUM && crtl->uses_pic_offset_table)
return true;
@@ -4600,11 +4600,12 @@ emit_save_register_window (rtx increment
insn = emit_insn (gen_save_register_window_1 (increment));
RTX_FRAME_RELATED_P (insn) = 1;
- /* The return address (%i7) is saved in %o7. */
+ /* The incoming return address (%o7) is saved in %i7. */
add_reg_note (insn, REG_CFA_REGISTER,
gen_rtx_SET (VOIDmode,
gen_rtx_REG (Pmode, RETURN_ADDR_REGNUM),
- gen_rtx_REG (Pmode, INCOMING_RETURN_ADDR_REGNUM)));
+ gen_rtx_REG (Pmode,
+ INCOMING_RETURN_ADDR_REGNUM)));
/* The window save event. */
add_reg_note (insn, REG_CFA_WINDOW_SAVE, const0_rtx);
@@ -4688,8 +4689,10 @@ sparc_expand_prologue (void)
; /* do nothing. */
else if (sparc_leaf_function_p)
{
+ rtx size_int_rtx = GEN_INT (-size);
+
if (size <= 4096)
- insn = emit_insn (gen_stack_pointer_inc (GEN_INT (-size)));
+ insn = emit_insn (gen_stack_pointer_inc (size_int_rtx));
else if (size <= 8192)
{
insn = emit_insn (gen_stack_pointer_inc (GEN_INT (-4096)));
@@ -4699,19 +4702,21 @@ sparc_expand_prologue (void)
}
else
{
- rtx reg = gen_rtx_REG (Pmode, 1);
- emit_move_insn (reg, GEN_INT (-size));
- insn = emit_insn (gen_stack_pointer_inc (reg));
+ rtx size_rtx = gen_rtx_REG (Pmode, 1);
+ emit_move_insn (size_rtx, size_int_rtx);
+ insn = emit_insn (gen_stack_pointer_inc (size_rtx));
add_reg_note (insn, REG_FRAME_RELATED_EXPR,
- gen_stack_pointer_inc (GEN_INT (-size)));
+ gen_stack_pointer_inc (size_int_rtx));
}
RTX_FRAME_RELATED_P (insn) = 1;
}
else
{
+ rtx size_int_rtx = GEN_INT (-size);
+
if (size <= 4096)
- emit_save_register_window (GEN_INT (-size));
+ emit_save_register_window (size_int_rtx);
else if (size <= 8192)
{
emit_save_register_window (GEN_INT (-4096));
@@ -4720,9 +4725,9 @@ sparc_expand_prologue (void)
}
else
{
- rtx reg = gen_rtx_REG (Pmode, 1);
- emit_move_insn (reg, GEN_INT (-size));
- emit_save_register_window (reg);
+ rtx size_rtx = gen_rtx_REG (Pmode, 1);
+ emit_move_insn (size_rtx, size_int_rtx);
+ emit_save_register_window (size_rtx);
}
}
@@ -4783,6 +4788,10 @@ sparc_flat_expand_prologue (void)
size_rtx = size_int_rtx = GEN_INT (-size);
+ /* We establish the frame (i.e. decrement the stack pointer) first, even
+ if we use a frame pointer, because we cannot clobber any call-saved
+ registers, including the frame pointer, if we haven't created a new
+ register save area, for the sake of compatibility with the ABI. */
if (size <= 4096)
insn = emit_insn (gen_stack_pointer_inc (size_int_rtx));
else if (size <= 8192 && !frame_pointer_needed)
@@ -4801,6 +4810,9 @@ sparc_flat_expand_prologue (void)
}
RTX_FRAME_RELATED_P (insn) = 1;
+ /* Ensure nothing is scheduled until after the frame is established. */
+ emit_insn (gen_blockage ());
+
if (frame_pointer_needed)
{
insn = emit_insn (gen_rtx_SET (VOIDmode, hard_frame_pointer_rtx,
@@ -4813,26 +4825,22 @@ sparc_flat_expand_prologue (void)
gen_rtx_SET (VOIDmode, hard_frame_pointer_rtx,
plus_constant (stack_pointer_rtx,
size)));
-
- /* Make sure nothing is scheduled until after the frame
- is established. */
- emit_insn (gen_blockage ());
}
if (return_addr_reg_needed_p (sparc_leaf_function_p))
{
- rtx i7 = gen_rtx_REG (Pmode, INCOMING_RETURN_ADDR_REGNUM);
- rtx o7 = gen_rtx_REG (Pmode, RETURN_ADDR_REGNUM);
+ rtx o7 = gen_rtx_REG (Pmode, INCOMING_RETURN_ADDR_REGNUM);
+ rtx i7 = gen_rtx_REG (Pmode, RETURN_ADDR_REGNUM);
- insn = emit_move_insn (o7, i7);
+ insn = emit_move_insn (i7, o7);
RTX_FRAME_RELATED_P (insn) = 1;
add_reg_note (insn, REG_CFA_REGISTER,
- gen_rtx_SET (VOIDmode, o7, i7));
+ gen_rtx_SET (VOIDmode, i7, o7));
/* Prevent this instruction from ever being considered dead,
even if this function has no epilogue. */
- emit_insn (gen_rtx_USE (VOIDmode, o7));
+ emit_insn (gen_rtx_USE (VOIDmode, i7));
}
}
