https://gcc.gnu.org/g:b9361e5bcbdf08ad6279d58ca63c4a260d34fcaf
commit r16-1686-gb9361e5bcbdf08ad6279d58ca63c4a260d34fcaf
Author: Shahab Vahedi <sha...@synopsys.com>
Date: Wed Jun 25 17:37:02 2025 +0300
ARC: Use intrinsics for __builtin_sub_overflow*()
This patch covers signed and unsigned subtractions. The generated code
would be something along these lines:
signed:
sub.f r0, r1, r2
b.v @label
unsigned:
sub.f r0, r1, r2
b.c @label
gcc/
* config/arc/arc.md (subsi3_v, subvsi4, subsi3_c): New patterns.
gcc/testsuite/
* gcc.target/arc/overflow-2.c: New file.
Diff:
---
gcc/config/arc/arc.md | 48 +++++++++++++++
gcc/testsuite/gcc.target/arc/overflow-2.c | 97 +++++++++++++++++++++++++++++++
2 files changed, 145 insertions(+)
diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md
index c81a7f19d228..2394eb8c001e 100644
--- a/gcc/config/arc/arc.md
+++ b/gcc/config/arc/arc.md
@@ -2964,6 +2964,54 @@ archs4x, archs4xd"
(set_attr "cpu_facility" "*,cd,*,*,*,*,*,*,*,*")
])
+(define_insn "subsi3_v"
+ [(set (match_operand:SI 0 "register_operand" "=r,r,r, r")
+ (minus:SI (match_operand:SI 1 "register_operand" "r,r,0, r")
+ (match_operand:SI 2 "nonmemory_operand" "r,L,I,C32")))
+ (set (reg:CC_V CC_REG)
+ (compare:CC_V (sign_extend:DI (minus:SI (match_dup 1)
+ (match_dup 2)))
+ (minus:DI (sign_extend:DI (match_dup 1))
+ (sign_extend:DI (match_dup 2)))))]
+ ""
+ "sub.f\\t%0,%1,%2"
+ [(set_attr "cond" "set")
+ (set_attr "type" "compare")
+ (set_attr "length" "4,4,4,8")])
+
+(define_expand "subvsi4"
+ [(match_operand:SI 0 "register_operand")
+ (match_operand:SI 1 "register_operand")
+ (match_operand:SI 2 "nonmemory_operand")
+ (label_ref (match_operand 3 "" ""))]
+ ""
+ "emit_insn (gen_subsi3_v (operands[0], operands[1], operands[2]));
+ arc_gen_unlikely_cbranch (NE, CC_Vmode, operands[3]);
+ DONE;")
+
+(define_insn "subsi3_c"
+ [(set (match_operand:SI 0 "register_operand" "=r,r,r, r")
+ (minus:SI (match_operand:SI 1 "register_operand" "r,r,0, r")
+ (match_operand:SI 2 "nonmemory_operand" "r,L,I,C32")))
+ (set (reg:CC_C CC_REG)
+ (compare:CC_C (match_dup 1)
+ (match_dup 2)))]
+ ""
+ "sub.f\\t%0,%1,%2"
+ [(set_attr "cond" "set")
+ (set_attr "type" "compare")
+ (set_attr "length" "4,4,4,8")])
+
+(define_expand "usubvsi4"
+ [(match_operand:SI 0 "register_operand")
+ (match_operand:SI 1 "register_operand")
+ (match_operand:SI 2 "nonmemory_operand")
+ (label_ref (match_operand 3 "" ""))]
+ ""
+ "emit_insn (gen_subsi3_c (operands[0], operands[1], operands[2]));
+ arc_gen_unlikely_cbranch (LTU, CC_Cmode, operands[3]);
+ DONE;")
+
(define_expand "subdi3"
[(set (match_operand:DI 0 "register_operand" "")
(minus:DI (match_operand:DI 1 "register_operand" "")
diff --git a/gcc/testsuite/gcc.target/arc/overflow-2.c
b/gcc/testsuite/gcc.target/arc/overflow-2.c
new file mode 100644
index 000000000000..b4de8c03b228
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arc/overflow-2.c
@@ -0,0 +1,97 @@
+/* { dg-do compile } */
+/* { dg-options "-O1" } */
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/*
+ * sub.f r0,r0,r1
+ * st_s r0,[r2]
+ * mov_s r0,1
+ * j_s.d [blink]
+ * mov.nv r0,0
+ */
+bool sub_overflow (int32_t a, int32_t b, int32_t *res)
+{
+ return __builtin_sub_overflow (a, b, res);
+}
+
+/*
+ * sub.f r0,r0,-1234
+ * st_s r0,[r1]
+ * mov_s r0,1
+ * j_s.d [blink]
+ * mov.nv r0,0
+ */
+bool subi_overflow (int32_t a, int32_t *res)
+{
+ return __builtin_sub_overflow (a, -1234, res);
+}
+
+/*
+ * sub.f r3,r0,r1
+ * st_s r3,[r2]
+ * j_s.d [blink]
+ * setlo r0,r0,r1
+ */
+bool usub_overflow (uint32_t a, uint32_t b, uint32_t *res)
+{
+ return __builtin_sub_overflow (a, b, res);
+}
+
+/*
+ * sub.f r2,r0,4321
+ * seths r0,4320,r0
+ * j_s.d [blink]
+ * st_s r2,[r1]
+ */
+bool usubi_overflow (uint32_t a, uint32_t *res)
+{
+ return __builtin_sub_overflow (a, 4321, res);
+}
+
+/*
+ * sub.f r0,r0,r1
+ * mov_s r0,1
+ * j_s.d [blink]
+ * mov.nv r0,0
+ */
+bool sub_overflow_p (int32_t a, int32_t b, int32_t res)
+{
+ return __builtin_sub_overflow_p (a, b, res);
+}
+
+/*
+ * sub.f r0,r0,-1000
+ * mov_s r0,1
+ * j_s.d [blink]
+ * mov.nv r0,0
+ */
+bool subi_overflow_p (int32_t a, int32_t res)
+{
+ return __builtin_sub_overflow_p (a, -1000, res);
+}
+
+/*
+ * j_s.d [blink]
+ * setlo r0,r0,r1
+ */
+bool usub_overflow_p (uint32_t a, uint32_t b, uint32_t res)
+{
+ return __builtin_sub_overflow_p (a, b, res);
+}
+
+/*
+ * seths r0,1999,r0
+ * j_s.d [blink]
+ */
+bool usubi_overflow_p (uint32_t a, uint32_t res)
+{
+ return __builtin_sub_overflow_p (a, 2000, res);
+}
+
+/* { dg-final { scan-assembler-times "sub.f\\s\+" 6 } } */
+/* { dg-final { scan-assembler-times "mov\.nv\\s\+" 4 } } */
+/* { dg-final { scan-assembler-times "setlo\\s\+" 2 } } */
+/* { dg-final { scan-assembler-times "seths\\s\+" 2 } } */
+/* { dg-final { scan-assembler-not "cmp" } } */
