https://gcc.gnu.org/g:7d5d2b879ae7636ca118fb4f3a08b22705cdeacb
commit r15-171-g7d5d2b879ae7636ca118fb4f3a08b22705cdeacb
Author: YunQiang Su <s...@gcc.gnu.org>
Date: Mon Apr 29 00:33:44 2024 +0800
expmed: TRUNCATE value1 if needed in store_bit_field_using_insv
PR target/113179.
In `store_bit_field_using_insv`, we just use SUBREG if value_mode
>= op_mode, while in some ports, a sign_extend will be needed,
such as MIPS64:
If either GPR rs or GPR rt does not contain sign-extended 32-bit
values (bits 63..31 equal), then the result of the operation is
UNPREDICTABLE.
The problem happens for the code like:
struct xx {
int a:4;
int b:24;
int c:3;
int d:1;
};
void xx (struct xx *a, long long b) {
a->d = b;
}
In the above code, the hard register contains `b`, may be note well
sign-extended.
gcc/
PR target/113179
* expmed.cc(store_bit_field_using_insv): TRUNCATE value1 if
needed.
gcc/testsuite
PR target/113179
* gcc.target/mips/pr113179.c: New tests.
Diff:
---
gcc/expmed.cc | 12 +++++++++---
gcc/testsuite/gcc.target/mips/pr113179.c | 18 ++++++++++++++++++
2 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/gcc/expmed.cc b/gcc/expmed.cc
index 4ec035e4843..20f3a36f38c 100644
--- a/gcc/expmed.cc
+++ b/gcc/expmed.cc
@@ -704,9 +704,15 @@ store_bit_field_using_insv (const extraction_insn *insv,
rtx op0,
}
else
{
- tmp = gen_lowpart_if_possible (op_mode, value1);
- if (! tmp)
- tmp = gen_lowpart (op_mode, force_reg (value_mode, value1));
+ if (targetm.mode_rep_extended (op_mode, value_mode) != UNKNOWN)
+ tmp = simplify_gen_unary (TRUNCATE, op_mode,
+ value1, value_mode);
+ else
+ {
+ tmp = gen_lowpart_if_possible (op_mode, value1);
+ if (! tmp)
+ tmp = gen_lowpart (op_mode, force_reg (value_mode, value1));
+ }
}
value1 = tmp;
}
diff --git a/gcc/testsuite/gcc.target/mips/pr113179.c
b/gcc/testsuite/gcc.target/mips/pr113179.c
new file mode 100644
index 00000000000..f32c5a16765
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/pr113179.c
@@ -0,0 +1,18 @@
+/* Check if the operand of INS is sign-extended on MIPS64. */
+/* { dg-options "-mips64r2 -mabi=64" } */
+/* { dg-skip-if "code quality test" { *-*-* } { "-O0" } { "" } } */
+
+struct xx {
+ int a:1;
+ int b:24;
+ int c:6;
+ int d:1;
+};
+
+long long xx (struct xx *a, long long b) {
+ a->d = b;
+ return b+1;
+}
+
+/* { dg-final { scan-assembler "\tsll\t\\\$3,\\\$5,0" } } */
+/* { dg-final { scan-assembler "\tdaddiu\t\\\$2,\\\$5,1" } } */
