Add a pattern for `(trunc)copysign ((extend)x, CST)`. Only the sign of
CST matters, not its value, so it can be simplified to
`copysign (x, -1.0/1.0)` depending on the sign of CST.
PR tree-optimization/112472
gcc/ChangeLog:
* match.pd ((trunc)copysign ((extend)x, CST) --> copysign (x,
-1.0/1.0)):
New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr112472.c: New test.
Signed-off-by: Eikansh Gupta <[email protected]>
---
gcc/match.pd | 14 +++++++++++++-
gcc/testsuite/gcc.dg/tree-ssa/pr112472.c | 15 +++++++++++++++
2 files changed, 28 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
diff --git a/gcc/match.pd b/gcc/match.pd
index ddf3b61638c..7edc73945fb 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -9343,7 +9343,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
&& TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@2))
&& direct_internal_fn_supported_p (IFN_COPYSIGN,
type, OPTIMIZE_FOR_BOTH))
- (IFN_COPYSIGN @0 @1))))
+ (IFN_COPYSIGN @0 @1)))
+ /* Simplify (trunc)copysign ((extend)x, CST) to copysign (x, -1.0/1.0). */
+ (simplify
+ (convert (copysigns (convert@2 @0) REAL_CST@1))
+ (if (optimize
+ && !HONOR_SNANS (@2)
+ && types_match (type, TREE_TYPE (@0))
+ && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@2))
+ && direct_internal_fn_supported_p (IFN_COPYSIGN,
+ type, OPTIMIZE_FOR_BOTH))
+ (if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (@1)))
+ (IFN_COPYSIGN @0 { build_minus_one_cst (type); })
+ (IFN_COPYSIGN @0 { build_one_cst (type); })))))
(for froms (BUILT_IN_FMAF BUILT_IN_FMA BUILT_IN_FMAL)
tos (IFN_FMA IFN_FMA IFN_FMA)
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
new file mode 100644
index 00000000000..30ef7636a50
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
@@ -0,0 +1,15 @@
+/* PR tree-optimization/112472 */
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-optimized" } */
+
+/* (trunc)copysign ((extend)a, CST) with a negative CST should be
+ simplified to .COPYSIGN (a, -1.0e+0). */
+float f(float a)
+{
+ return (float)__builtin_copysign(a, -3.0);
+}
+
+/* { dg-final { scan-tree-dump-not "= __builtin_copysign" "optimized" } } */
+/* { dg-final { scan-tree-dump-not " double " "optimized" { target
ifn_copysign } } } */
+/* { dg-final { scan-tree-dump-times ".COPYSIGN" 1 "optimized" { target
ifn_copysign } } } */
+/* { dg-final { scan-tree-dump-times "-1.0e\\+0" 1 "optimized" { target
ifn_copysign } } } */
--
2.34.1
>From bcf5f5a3836a3c0841f70dc98b964003fb3d1c89 Mon Sep 17 00:00:00 2001
From: Eikansh Gupta <[email protected]>
Date: Mon, 15 Jun 2026 12:19:45 +0530
Subject: [PATCH v3 2/2] MATCH: Simplify `(trunc)abs ((extend)x)` to `abs (x)`
[PR112472]
When the second argument of copysign is a non-negative constant, the
inner copysign is canonicalized to abs before the copysign pattern can
match, leaving (trunc)abs ((extend)x) with a redundant extend/truncate.
Add a pattern so the non-negative-constant copysign case is fully optimized too.
PR tree-optimization/112472
gcc/ChangeLog:
* match.pd ((trunc)abs (extend x) --> abs (x)): New pattern.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/pr112472.c: Add non-negative constant case.
Signed-off-by: Eikansh Gupta <[email protected]>
---
gcc/match.pd | 9 +++++++++
gcc/testsuite/gcc.dg/tree-ssa/pr112472.c | 9 +++++++++
2 files changed, 18 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 7edc73945fb..d627aa4728e 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -9357,6 +9357,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(IFN_COPYSIGN @0 { build_minus_one_cst (type); })
(IFN_COPYSIGN @0 { build_one_cst (type); })))))
+/* (trunc)abs (extend x) --> abs (x) */
+(simplify
+ (convert (abs (convert@1 @0)))
+ (if (optimize
+ && !HONOR_SNANS (@1)
+ && types_match (type, TREE_TYPE (@0))
+ && TYPE_PRECISION (type) < TYPE_PRECISION (TREE_TYPE (@1)))
+ (abs @0)))
+
(for froms (BUILT_IN_FMAF BUILT_IN_FMA BUILT_IN_FMAL)
tos (IFN_FMA IFN_FMA IFN_FMA)
(simplify
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
b/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
index 30ef7636a50..6838c73c77e 100644
--- a/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr112472.c
@@ -9,7 +9,16 @@ float f(float a)
return (float)__builtin_copysign(a, -3.0);
}
+/* With a non-negative CST, copysign is canonicalized to abs, so this
+ becomes (float)abs((double)a) and is then simplified to abs(a),
+ dropping the wider type. */
+float f2(float a)
+{
+ return (float)__builtin_copysign(a, 5.0);
+}
+
/* { dg-final { scan-tree-dump-not "= __builtin_copysign" "optimized" } } */
/* { dg-final { scan-tree-dump-not " double " "optimized" { target
ifn_copysign } } } */
/* { dg-final { scan-tree-dump-times ".COPYSIGN" 1 "optimized" { target
ifn_copysign } } } */
/* { dg-final { scan-tree-dump-times "-1.0e\\+0" 1 "optimized" { target
ifn_copysign } } } */
+/* { dg-final { scan-tree-dump-times " ABS_EXPR " 1 "optimized" { target
ifn_copysign } } } */
--
2.34.1
