From: Xi Ruoyao <xry111@xry111.site>
Date: Sat, 24 Sep 2022 12:47:22 +0000 (+0800)
Subject: LoongArch: Use UNSPEC for fmin/fmax RTL pattern [PR105414]
X-Git-Tag: basepoints/gcc-14~4293
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b48d7ff3570fa0ebe7790275cf020d8885120338;p=thirdparty%2Fgcc.git

LoongArch: Use UNSPEC for fmin/fmax RTL pattern [PR105414]

I made a mistake defining fmin/fmax RTL patterns in r13-2085: I used
smin and smax in the definition mistakenly.  This causes the optimizer
to perform constant folding as if fmin/fmax was "really" smin/smax
operations even with -fsignaling-nans.  Then pr105414.c fails.

We don't have fmin/fmax RTL codes for now (PR107013) so we can only use
an UNSPEC for fmin and fmax patterns.

gcc/ChangeLog:

	PR tree-optimization/105414
	* config/loongarch/loongarch.md (UNSPEC_FMAX): New unspec.
	(UNSPEC_FMIN): Likewise.
	(fmax<mode>3): Use UNSPEC_FMAX instead of smax.
	(fmin<mode>3): Use UNSPEC_FMIN instead of smin.
---

diff --git a/gcc/config/loongarch/loongarch.md b/gcc/config/loongarch/loongarch.md
index 3787fd8230f4..214b14bddd39 100644
--- a/gcc/config/loongarch/loongarch.md
+++ b/gcc/config/loongarch/loongarch.md
@@ -35,6 +35,8 @@
   ;; Floating point unspecs.
   UNSPEC_FRINT
   UNSPEC_FCLASS
+  UNSPEC_FMAX
+  UNSPEC_FMIN
 
   ;; Override return address for exception handling.
   UNSPEC_EH_RETURN
@@ -1032,8 +1034,9 @@
 
 (define_insn "fmax<mode>3"
   [(set (match_operand:ANYF 0 "register_operand" "=f")
-	(smax:ANYF (match_operand:ANYF 1 "register_operand" "f")
-		   (match_operand:ANYF 2 "register_operand" "f")))]
+	(unspec:ANYF [(use (match_operand:ANYF 1 "register_operand" "f"))
+		      (use (match_operand:ANYF 2 "register_operand" "f"))]
+		     UNSPEC_FMAX))]
   ""
   "fmax.<fmt>\t%0,%1,%2"
   [(set_attr "type" "fmove")
@@ -1041,8 +1044,9 @@
 
 (define_insn "fmin<mode>3"
   [(set (match_operand:ANYF 0 "register_operand" "=f")
-	(smin:ANYF (match_operand:ANYF 1 "register_operand" "f")
-		   (match_operand:ANYF 2 "register_operand" "f")))]
+	(unspec:ANYF [(use (match_operand:ANYF 1 "register_operand" "f"))
+		      (use (match_operand:ANYF 2 "register_operand" "f"))]
+		     UNSPEC_FMIN))]
   ""
   "fmin.<fmt>\t%0,%1,%2"
   [(set_attr "type" "fmove")