Add an optional `align' parameter to choose_baseaddr, allowing the
caller to request an address that is aligned to some boundary. Modify
ix86_emit_save_regs_using_mov and ix86_emit_restore_regs_using_mov use
optimally aligned memory when such a base register is available.
Signed-off-by: Daniel Santos <daniel.san...@pobox.com>
---
gcc/config/i386/i386.c | 111 ++++++++++++++++++++++++++++++++++++++----------
gcc/config/i386/winnt.c | 3 +-
2 files changed, 90 insertions(+), 24 deletions(-)
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 7923486157d..e8a4ba6fe8d 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -12801,15 +12801,39 @@ static inline bool fp_valid_at (HOST_WIDE_INT
cfa_offset)
&& cfa_offset >= fs.sp_realigned_offset);
}
-/* Return an RTX that points to CFA_OFFSET within the stack frame.
- The valid base registers are taken from CFUN->MACHINE->FS. */
+/* Choose a base register based upon alignment requested, speed and/or
+ size. */
-static rtx
-choose_baseaddr (HOST_WIDE_INT cfa_offset)
+static void choose_basereg (HOST_WIDE_INT cfa_offset, rtx &base_reg,
+ HOST_WIDE_INT &base_offset,
+ unsigned int align_reqested, unsigned int *align)
{
const struct machine_function *m = cfun->machine;
- rtx base_reg = NULL;
- HOST_WIDE_INT base_offset = 0;
+ unsigned int hfp_align;
+ unsigned int drap_align;
+ unsigned int sp_align;
+ bool hfp_ok = fp_valid_at (cfa_offset);
+ bool drap_ok = m->fs.drap_valid;
+ bool sp_ok = sp_valid_at (cfa_offset);
+
+ hfp_align = drap_align = sp_align = INCOMING_STACK_BOUNDARY;
+
+ /* Filter out any registers that don't meet the requested alignment
+ criteria. */
+ if (align_reqested)
+ {
+ if (m->fs.realigned)
+ hfp_align = drap_align = sp_align = crtl->stack_alignment_needed;
+ /* SEH unwind code does do not currently support REG_CFA_EXPRESSION
+ notes (which we would need to use a realigned stack pointer),
+ so disable on SEH targets. */
+ else if (m->fs.sp_realigned)
+ sp_align = crtl->stack_alignment_needed;
+
+ hfp_ok = hfp_ok && hfp_align >= align_reqested;
+ drap_ok = drap_ok && drap_align >= align_reqested;
+ sp_ok = sp_ok && sp_align >= align_reqested;
+ }
if (m->use_fast_prologue_epilogue)
{
@@ -12818,17 +12842,17 @@ choose_baseaddr (HOST_WIDE_INT cfa_offset)
while DRAP must be reloaded within the epilogue. But choose either
over the SP due to increased encoding size. */
- if (m->fs.fp_valid)
+ if (hfp_ok)
{
base_reg = hard_frame_pointer_rtx;
base_offset = m->fs.fp_offset - cfa_offset;
}
- else if (m->fs.drap_valid)
+ else if (drap_ok)
{
base_reg = crtl->drap_reg;
base_offset = 0 - cfa_offset;
}
- else if (m->fs.sp_valid)
+ else if (sp_ok)
{
base_reg = stack_pointer_rtx;
base_offset = m->fs.sp_offset - cfa_offset;
@@ -12841,13 +12865,13 @@ choose_baseaddr (HOST_WIDE_INT cfa_offset)
/* Choose the base register with the smallest address encoding.
With a tie, choose FP > DRAP > SP. */
- if (m->fs.sp_valid)
+ if (sp_ok)
{
base_reg = stack_pointer_rtx;
base_offset = m->fs.sp_offset - cfa_offset;
len = choose_baseaddr_len (STACK_POINTER_REGNUM, base_offset);
}
- if (m->fs.drap_valid)
+ if (drap_ok)
{
toffset = 0 - cfa_offset;
tlen = choose_baseaddr_len (REGNO (crtl->drap_reg), toffset);
@@ -12858,7 +12882,7 @@ choose_baseaddr (HOST_WIDE_INT cfa_offset)
len = tlen;
}
}
- if (m->fs.fp_valid)
+ if (hfp_ok)
{
toffset = m->fs.fp_offset - cfa_offset;
tlen = choose_baseaddr_len (HARD_FRAME_POINTER_REGNUM, toffset);
@@ -12870,8 +12894,40 @@ choose_baseaddr (HOST_WIDE_INT cfa_offset)
}
}
}
- gcc_assert (base_reg != NULL);
+ /* Set the align return value. */
+ if (align)
+ {
+ if (base_reg == stack_pointer_rtx)
+ *align = sp_align;
+ else if (base_reg == crtl->drap_reg)
+ *align = drap_align;
+ else if (base_reg == hard_frame_pointer_rtx)
+ *align = hfp_align;
+ }
+}
+
+/* Return an RTX that points to CFA_OFFSET within the stack frame and
+ the alignment of address. If align is non-null, it should point to
+ an alignment value (in bits) that is preferred or zero and will
+ recieve the alignment of the base register that was selected. The
+ valid base registers are taken from CFUN->MACHINE->FS. */
+
+static rtx
+choose_baseaddr (HOST_WIDE_INT cfa_offset, unsigned int *align)
+{
+ rtx base_reg = NULL;
+ HOST_WIDE_INT base_offset = 0;
+
+ /* If a specific alignment is requested, try to get a base register
+ with that alignment first. */
+ if (align && *align)
+ choose_basereg (cfa_offset, base_reg, base_offset, *align, align);
+
+ if (!base_reg)
+ choose_basereg (cfa_offset, base_reg, base_offset, 0, align);
+
+ gcc_assert (base_reg != NULL);
return plus_constant (Pmode, base_reg, base_offset);
}
@@ -12900,13 +12956,14 @@ ix86_emit_save_reg_using_mov (machine_mode mode,
unsigned int regno,
struct machine_function *m = cfun->machine;
rtx reg = gen_rtx_REG (mode, regno);
rtx mem, addr, base, insn;
- unsigned int align;
+ unsigned int align = GET_MODE_ALIGNMENT (mode);
- addr = choose_baseaddr (cfa_offset);
+ addr = choose_baseaddr (cfa_offset, &align);
mem = gen_frame_mem (mode, addr);
- /* The location is aligned up to INCOMING_STACK_BOUNDARY. */
- align = MIN (GET_MODE_ALIGNMENT (mode), INCOMING_STACK_BOUNDARY);
+ /* The location aligment depends upon the base register. */
+ align = MIN (GET_MODE_ALIGNMENT (mode), align);
+ gcc_assert (! (cfa_offset & (align / BITS_PER_UNIT - 1)));
set_mem_align (mem, align);
insn = emit_insn (gen_rtx_SET (mem, reg));
@@ -12946,6 +13003,13 @@ ix86_emit_save_reg_using_mov (machine_mode mode,
unsigned int regno,
}
}
+ else if (base == stack_pointer_rtx && m->fs.sp_realigned
+ && cfa_offset >= m->fs.sp_realigned_offset)
+ {
+ gcc_checking_assert (stack_realign_fp);
+ add_reg_note (insn, REG_CFA_EXPRESSION, gen_rtx_SET (mem, reg));
+ }
+
/* The memory may not be relative to the current CFA register,
which means that we may need to generate a new pattern for
use by the unwind info. */
@@ -14350,7 +14414,7 @@ ix86_expand_prologue (void)
/* vDRAP is setup but after reload it turns out stack realign
isn't necessary, here we will emit prologue to setup DRAP
without stack realign adjustment */
- t = choose_baseaddr (0);
+ t = choose_baseaddr (0, NULL);
emit_insn (gen_rtx_SET (crtl->drap_reg, t));
}
@@ -14487,7 +14551,7 @@ ix86_emit_restore_regs_using_mov (HOST_WIDE_INT
cfa_offset,
rtx mem;
rtx_insn *insn;
- mem = choose_baseaddr (cfa_offset);
+ mem = choose_baseaddr (cfa_offset, NULL);
mem = gen_frame_mem (word_mode, mem);
insn = emit_move_insn (reg, mem);
@@ -14524,13 +14588,14 @@ ix86_emit_restore_sse_regs_using_mov (HOST_WIDE_INT
cfa_offset,
{
rtx reg = gen_rtx_REG (V4SFmode, regno);
rtx mem;
- unsigned int align;
+ unsigned int align = GET_MODE_ALIGNMENT (V4SFmode);
- mem = choose_baseaddr (cfa_offset);
+ mem = choose_baseaddr (cfa_offset, &align);
mem = gen_rtx_MEM (V4SFmode, mem);
- /* The location is aligned up to INCOMING_STACK_BOUNDARY. */
- align = MIN (GET_MODE_ALIGNMENT (V4SFmode), INCOMING_STACK_BOUNDARY);
+ /* The location aligment depends upon the base register. */
+ align = MIN (GET_MODE_ALIGNMENT (V4SFmode), align);
+ gcc_assert (! (cfa_offset & (align / BITS_PER_UNIT - 1)));
set_mem_align (mem, align);
emit_insn (gen_rtx_SET (reg, mem));
diff --git a/gcc/config/i386/winnt.c b/gcc/config/i386/winnt.c
index f89e7d00fe2..8272c7fddc1 100644
--- a/gcc/config/i386/winnt.c
+++ b/gcc/config/i386/winnt.c
@@ -1128,7 +1128,8 @@ i386_pe_seh_unwind_emit (FILE *asm_out_file, rtx_insn
*insn)
case REG_CFA_DEF_CFA:
case REG_CFA_EXPRESSION:
- /* Only emitted with DRAP, which we disable. */
+ /* Only emitted with DRAP and aligned memory access using a
+ realigned SP, both of which we disable. */
gcc_unreachable ();
break;
--
2.11.0
