We have been using CCmode, which is not correct for this case.
Mirror the same code from the arm target.
* config/aarch64/aarch64.c (aarch64_select_cc_mode):
Recognize usub*_carryinC patterns.
* config/aarch64/aarch64.md (usubvti4): Use CC_NOTC.
(usub<GPI>3_carryinC): Likewise.
(*usub<GPI>3_carryinC_z1): Likewise.
(*usub<GPI>3_carryinC_z2): Likewise.
(*usub<GPI>3_carryinC): Likewise.
---
gcc/config/aarch64/aarch64.c | 9 +++++++++
gcc/config/aarch64/aarch64.md | 18 +++++++++---------
2 files changed, 18 insertions(+), 9 deletions(-)
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index c09b7bcb7f0..d80afc36889 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -9532,6 +9532,15 @@ aarch64_select_cc_mode (RTX_CODE code, rtx x, rtx y)
&& const_dword_umaxp1 (y, mode_x))
return CC_NOTCmode;
+ /* A test for unsigned overflow from a subtract with borrow. */
+ if ((mode_x == DImode || mode_x == TImode)
+ && (code == GEU || code == LTU)
+ && code_x == ZERO_EXTEND
+ && ((GET_CODE (y) == PLUS
+ && aarch64_borrow_operation (XEXP (y, 0), mode_x))
+ || aarch64_borrow_operation (y, mode_x)))
+ return CC_NOTCmode;
+
/* A test for signed overflow. */
if ((mode_x == DImode || mode_x == TImode)
&& (code == NE || code == EQ)
diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 7d4a63f9a2a..a0a872c6d94 100644
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -2954,7 +2954,7 @@
CODE_FOR_subdi3_compare1,
CODE_FOR_subdi3_compare1,
CODE_FOR_usubdi3_carryinC);
- aarch64_gen_unlikely_cbranch (LTU, CCmode, operands[3]);
+ aarch64_gen_unlikely_cbranch (LTU, CC_NOTCmode, operands[3]);
DONE;
})
@@ -3367,8 +3367,8 @@
(define_expand "usub<GPI:mode>3_carryinC"
[(parallel
- [(set (reg:CC CC_REGNUM)
- (compare:CC
+ [(set (reg:CC_NOTC CC_REGNUM)
+ (compare:CC_NOTC
(zero_extend:<DWI>
(match_operand:GPI 1 "aarch64_reg_or_zero"))
(plus:<DWI>
@@ -3383,8 +3383,8 @@
)
(define_insn "*usub<GPI:mode>3_carryinC_z1"
- [(set (reg:CC CC_REGNUM)
- (compare:CC
+ [(set (reg:CC_NOTC CC_REGNUM)
+ (compare:CC_NOTC
(const_int 0)
(plus:<DWI>
(zero_extend:<DWI>
@@ -3400,8 +3400,8 @@
)
(define_insn "*usub<GPI:mode>3_carryinC_z2"
- [(set (reg:CC CC_REGNUM)
- (compare:CC
+ [(set (reg:CC_NOTC CC_REGNUM)
+ (compare:CC_NOTC
(zero_extend:<DWI>
(match_operand:GPI 1 "register_operand" "r"))
(match_operand:<DWI> 2 "aarch64_borrow_operation" "")))
@@ -3415,8 +3415,8 @@
)
(define_insn "*usub<GPI:mode>3_carryinC"
- [(set (reg:CC CC_REGNUM)
- (compare:CC
+ [(set (reg:CC_NOTC CC_REGNUM)
+ (compare:CC_NOTC
(zero_extend:<DWI>
(match_operand:GPI 1 "register_operand" "r"))
(plus:<DWI>
--
2.20.1
