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PowerPC: rename some functions.

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gcc/
2020-09-11  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_maybe_emit_maxc_minc): Rename
	from rs6000_emit_p9_fp_minmax.  Change return type to bool.  Add
	comments to document NaN/signed zero behavior.
	(rs6000_maybe_emit_fp_cmove): Rename from rs6000_emit_p9_fp_cmove.
	(have_compare_and_set_mask): New helper function.
	(rs6000_emit_cmove): Update calls to new names and the new helper
	function.
This commit is contained in:
Michael Meissner 2020-09-11 18:10:14 -04:00
parent 9d377c280c
commit e73f586c93
1 changed files with 69 additions and 24 deletions
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93
gcc/config/rs6000/rs6000.c
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@ -15057,13 +15057,33 @@ rs6000_emit_vector_cond_expr (rtx dest, rtx op_true, rtx op_false,
return 1;
}
/* ISA 3.0 (power9) minmax subcase to emit a XSMAXCDP or XSMINCDP instruction
for SF/DF scalars. Move TRUE_COND to DEST if OP of the operands of the last
comparison is nonzero/true, FALSE_COND if it is zero/false. Return 0 if the
hardware has no such operation. */
/* Possibly emit the xsmaxcdp and xsmincdp instructions to emit a maximum or
minimum with "C" semantics.
static int
rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx true_cond, rtx false_cond)
Unless you use -ffast-math, you can't use these instructions to replace
conditions that implicitly reverse the condition because the comparison
might generate a NaN or signed zer0.
I.e. the following can be replaced all of the time
ret = (op1 > op2) ? op1 : op2 ; generate xsmaxcdp
ret = (op1 >= op2) ? op1 : op2 ; generate xsmaxcdp
ret = (op1 < op2) ? op1 : op2; ; generate xsmincdp
ret = (op1 <= op2) ? op1 : op2; ; generate xsmincdp
The following can be replaced only if -ffast-math is used:
ret = (op1 < op2) ? op2 : op1 ; generate xsmaxcdp
ret = (op1 <= op2) ? op2 : op1 ; generate xsmaxcdp
ret = (op1 > op2) ? op2 : op1; ; generate xsmincdp
ret = (op1 >= op2) ? op2 : op1; ; generate xsmincdp
Move TRUE_COND to DEST if OP of the operands of the last comparison is
nonzero/true, FALSE_COND if it is zero/false.
Return false if we can't generate the appropriate minimum or maximum, and
true if we can did the minimum or maximum. */
static bool
rs6000_maybe_emit_maxc_minc (rtx dest, rtx op, rtx true_cond, rtx false_cond)
{
enum rtx_code code = GET_CODE (op);
rtx op0 = XEXP (op, 0);
@ -15073,14 +15093,14 @@ rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx true_cond, rtx false_cond)
bool max_p = false;
if (result_mode != compare_mode)
return 0;
return false;
if (code == GE || code == GT)
max_p = true;
else if (code == LE || code == LT)
max_p = false;
else
return 0;
return false;
if (rtx_equal_p (op0, true_cond) && rtx_equal_p (op1, false_cond))
;
@ -15093,19 +15113,23 @@ rs6000_emit_p9_fp_minmax (rtx dest, rtx op, rtx true_cond, rtx false_cond)
max_p = !max_p;
else
return 0;
return false;
rs6000_emit_minmax (dest, max_p ? SMAX : SMIN, op0, op1);
return 1;
return true;
}
/* ISA 3.0 (power9) conditional move subcase to emit XSCMP{EQ,GE,GT,NE}DP and
XXSEL instructions for SF/DF scalars. Move TRUE_COND to DEST if OP of the
operands of the last comparison is nonzero/true, FALSE_COND if it is
zero/false. Return 0 if the hardware has no such operation. */
/* Possibly emit a floating point conditional move by generating a compare that
sets a mask instruction and a XXSEL select instruction.
static int
rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
Move TRUE_COND to DEST if OP of the operands of the last comparison is
nonzero/true, FALSE_COND if it is zero/false.
Return false if the operation cannot be generated, and true if we could
generate the instruction. */
static bool
rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
{
enum rtx_code code = GET_CODE (op);
rtx op0 = XEXP (op, 0);
@ -15133,7 +15157,7 @@ rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
break;
default:
return 0;
return false;
}
/* Generate: [(parallel [(set (dest)
@ -15153,7 +15177,28 @@ rs6000_emit_p9_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
emit_insn (gen_rtx_PARALLEL (VOIDmode,
gen_rtvec (2, cmove_rtx, clobber_rtx)));
return 1;
return true;
}
/* Helper function to return true if the target has instructions to do a
compare and set mask instruction that can be used with XXSEL to implement a
conditional move. It is also assumed that such a target also supports the
"C" minimum and maximum instructions. */
static bool
have_compare_and_set_mask (machine_mode mode)
{
switch (mode)
{
case SFmode:
case DFmode:
return TARGET_P9_MINMAX;
default:
break;
}
return false;
}
/* Emit a conditional move: move TRUE_COND to DEST if OP of the
@ -15182,15 +15227,15 @@ rs6000_emit_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
if (GET_MODE (false_cond) != result_mode)
return false;
/* See if we can use the ISA 3.0 (power9) min/max/compare functions. */
if (TARGET_P9_MINMAX
&& (compare_mode == SFmode || compare_mode == DFmode)
&& (result_mode == SFmode || result_mode == DFmode))
/* See if we can use the "C" minimum, "C" maximum, and compare and set mask
instructions. */
if (have_compare_and_set_mask (compare_mode)
&& have_compare_and_set_mask (result_mode))
{
if (rs6000_emit_p9_fp_minmax (dest, op, true_cond, false_cond))
if (rs6000_maybe_emit_maxc_minc (dest, op, true_cond, false_cond))
return true;
if (rs6000_emit_p9_fp_cmove (dest, op, true_cond, false_cond))
if (rs6000_maybe_emit_fp_cmove (dest, op, true_cond, false_cond))
return true;
}