@@ -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;
}
Here is the patch that I applied: From 1a2e0742e3e3c45f75d0ce31c45a7778c8d1f45e Mon Sep 17 00:00:00 2001 From: Michael Meissner <meissner@linux.ibm.com> Date: Fri, 11 Sep 2020 16:57:13 -0400 Subject: [PATCH] PowerPC: rename some functions. 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. --- gcc/config/rs6000/rs6000.c | 93 ++++++++++++++++++++++++++++---------- 1 file changed, 69 insertions(+), 24 deletions(-)