diff options
| author | Greg McGary <gkm@rivosinc.com> | 2024-03-03 14:49:49 -0700 |
|---|---|---|
| committer | Jeff Law <jlaw@ventanamicro.com> | 2024-03-03 14:50:34 -0700 |
| commit | 24975a9195743e8eb4ca213f35b9221d4eeb6b59 (patch) | |
| tree | 0b66a8ee8cd9d6da2af6d894b2100a3b3728207d | |
| parent | 5cc61212b71a3e1264c8a9c0c35e13474be04f87 (diff) | |
[PATCH] combine: Don't simplify paradoxical SUBREG on WORD_REGISTER_OPERATIONS [PR113010]
The sign-bit-copies of a sign-extending load cannot be known until runtime on
WORD_REGISTER_OPERATIONS targets, except in the case of a zero-extending MEM
load. See the fix for PR112758.
gcc/
PR rtl-optimization/113010
* combine.cc (simplify_comparison): Simplify a SUBREG on
WORD_REGISTER_OPERATIONS targets only if it is a zero-extending
MEM load.
gcc/testsuite
* gcc.c-torture/execute/pr113010.c: New test.
| -rw-r--r-- | gcc/combine.cc | 15 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.c-torture/execute/pr113010.c | 9 |
2 files changed, 22 insertions, 2 deletions
diff --git a/gcc/combine.cc b/gcc/combine.cc index 76543d85b7c..b09200d757e 100644 --- a/gcc/combine.cc +++ b/gcc/combine.cc @@ -12550,9 +12550,20 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1) } /* If the inner mode is narrower and we are extracting the low part, - we can treat the SUBREG as if it were a ZERO_EXTEND. */ + we can treat the SUBREG as if it were a ZERO_EXTEND ... */ if (paradoxical_subreg_p (op0)) - ; + { + if (WORD_REGISTER_OPERATIONS + && GET_MODE_PRECISION (inner_mode) < BITS_PER_WORD + /* On WORD_REGISTER_OPERATIONS targets the bits + beyond sub_mode aren't considered undefined, + so optimize only if it is a MEM load when MEM loads + zero extend, because then the upper bits are all zero. */ + && !(MEM_P (SUBREG_REG (op0)) + && load_extend_op (inner_mode) == ZERO_EXTEND)) + break; + /* FALLTHROUGH to case ZERO_EXTEND */ + } else if (subreg_lowpart_p (op0) && GET_MODE_CLASS (mode) == MODE_INT && is_int_mode (GET_MODE (SUBREG_REG (op0)), &inner_mode) diff --git a/gcc/testsuite/gcc.c-torture/execute/pr113010.c b/gcc/testsuite/gcc.c-torture/execute/pr113010.c new file mode 100644 index 00000000000..2c84333f5dc --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr113010.c @@ -0,0 +1,9 @@ +int minus_1 = -1; + +int +main () +{ + if ((0, 0xffffffffull) >= minus_1) + __builtin_abort (); + return 0; +} |