[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.
This patch adds the support for the IEEE 128-bit floating point C minimum and
maximum instructions. The next patch will add the support for using the
compare and set mask instruction to implement conditional moves.
This patch does not try to re-use the code used for SF/DF min/max
support. It defines a separate insn for the IEEE 128-bit support. It
uses the code iterator <minmax> to simplify adding both operations.
GCC will not convert ?: operations into using min/max instructions provided in
this patch unless the user uses -Ofast or similar switches due to issues with
NaNs. The next patch that adds conditional move instructions will enable the
?: conversion in many cases.
I have done bootstrap builds with this patch on the following 3 systems:
1) power9 running LE Linux using --with-cpu=power9
2) power8 running BE Linux using --with-cpu=power8, testing both
32/64-bit.
3) power10 prototype running LE Linux using --with-cpu=power10.
There were no regressions to the tests, and the new test added passed. Can I
check these patches into trunk branch for GCC 12?
I would like to check these patches into GCC 11 after a cooling off period, but
I can also not do the backport if desired.
gcc/
2021-05-18 Michael Meissner <meiss...@linux.ibm.com>
* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp
instructions.
* config/rs6000/rs6000.md (s<minmax><mode>3, IEEE128 iterator):
New insns.
gcc/testsuite/
2021-05-18 Michael Meissner <meiss...@linux.ibm.com>
* gcc.target/powerpc/float128-minmax-2.c: New test.
* gcc.target/powerpc/float128-minmax.c: Turn off power10 code
generation.
---
gcc/config/rs6000/rs6000.c | 3 ++-
gcc/config/rs6000/rs6000.md | 11 +++++++++++
.../gcc.target/powerpc/float128-minmax-2.c | 15 +++++++++++++++
.../gcc.target/powerpc/float128-minmax.c | 7 +++++++
4 files changed, 35 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 0d0595dddd6..fdaf12aeda0 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx
op0, rtx op1)
/* VSX/altivec have direct min/max insns. */
if ((code == SMAX || code == SMIN)
&& (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
- || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
+ || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
+ || (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode))))
{
emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
return;
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 0bfeb24d9e8..3a1bc1f8547 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5196,6 +5196,17 @@ (define_insn "*s<minmax><mode>3_vsx"
}
[(set_attr "type" "fp")])
+;; Min/max for ISA 3.1 IEEE 128-bit floating point
+(define_insn "s<minmax><mode>3"
+ [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+ (fp_minmax:IEEE128
+ (match_operand:IEEE128 1 "altivec_register_operand" "v")
+ (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
+ "TARGET_POWER10"
+ "xs<minmax>cqp %0,%1,%2"
+ [(set_attr "type" "vecfloat")
+ (set_attr "size" "128")])
+
;; The conditional move instructions allow us to perform max and min operations
;; even when we don't have the appropriate max/min instruction using the FSEL
;; instruction.
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
new file mode 100644
index 00000000000..c71ba08c9f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+ call. */
+TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
+TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
index fe397518f2f..c3af759c0b9 100644
--- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
@@ -3,6 +3,13 @@
/* { dg-require-effective-target float128 } */
/* { dg-options "-mpower9-vector -O2 -ffast-math" } */
+/* If the compiler was configured to automatically generate power10 support
with
+ --with-cpu=power10, turn it off. Otherwise, it will generate XXMAXCQP and
+ XXMINCQP instructions. */
+#ifdef _ARCH_PWR10
+#pragma GCC target ("cpu=power9")
+#endif
+
#ifndef TYPE
#define TYPE _Float128
#endif
--
2.31.1
--
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797
