Currently we expand `{}` and store zeros to the stack and then do a full
mode load back. This is a waste, instead we should just use the zero cst
in the mode that fits the bitsize.
Boostrapped and tested on x86_64-linux-gnu.
Build and tested for aarch64-linux-gnu.
PR middle-end/110459
gcc/ChangeLog:
* expr.cc (store_field): For `{}` exp where bitsize is known
to be less than BITS_PER_WORD, use zero cst.
gcc/testsuite/ChangeLog:
* g++.target/aarch64/array-return-1.C: New test.
* g++.target/i386/array-return-1.C: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
---
gcc/expr.cc | 10 ++++++++-
.../g++.target/aarch64/array-return-1.C | 22 +++++++++++++++++++
.../g++.target/i386/array-return-1.C | 20 +++++++++++++++++
3 files changed, 51 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.target/aarch64/array-return-1.C
create mode 100644 gcc/testsuite/g++.target/i386/array-return-1.C
diff --git a/gcc/expr.cc b/gcc/expr.cc
index 1eeefa1cadc..af03809cad8 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -8243,7 +8243,15 @@ store_field (rtx target, poly_int64 bitsize, poly_int64
bitpos,
}
}
- temp = expand_normal (exp);
+ if (TREE_CODE (exp) == CONSTRUCTOR
+ && CONSTRUCTOR_NELTS (exp) == 0
+ && known_le (bitsize, BITS_PER_WORD))
+ {
+ machine_mode temp_mode = smallest_int_mode_for_size (bitsize).require
();
+ temp = CONST0_RTX (temp_mode);
+ }
+ else
+ temp = expand_normal (exp);
/* We don't support variable-sized BLKmode bitfields, since our
handling of BLKmode is bound up with the ability to break
diff --git a/gcc/testsuite/g++.target/aarch64/array-return-1.C
b/gcc/testsuite/g++.target/aarch64/array-return-1.C
new file mode 100644
index 00000000000..7c0aa480775
--- /dev/null
+++ b/gcc/testsuite/g++.target/aarch64/array-return-1.C
@@ -0,0 +1,22 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+// { dg-final { check-function-bodies "**" "" "" { target { le } } } }
+
+// PR middle-end/110459
+
+/*
+**_Z7sample2c:
+** and w0, w0, 255
+** ret
+*/
+
+struct array {
+ char data[4];
+};
+
+// There should be no adjustment to the stack
+// { dg-final { scan-assembler-not "sp, sp," } }
+auto sample2(char c) {
+ array buffer = {c, 0, 0, 0};
+ return buffer;
+}
diff --git a/gcc/testsuite/g++.target/i386/array-return-1.C
b/gcc/testsuite/g++.target/i386/array-return-1.C
new file mode 100644
index 00000000000..f11905d01e5
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/array-return-1.C
@@ -0,0 +1,20 @@
+// { dg-do compile }
+// { dg-options "-O2" }
+// { dg-final { check-function-bodies "**" "" "" { target { ! ia32 } } } }
+
+// PR middle-end/110459
+
+/*
+**_Z7sample2c:
+** movzbl %dil, %eax
+** ret
+*/
+
+struct array {
+ char data[4];
+};
+
+array sample2(char c) {
+ array buffer = {c, 0, 0, 0};
+ return buffer;
+}
--
2.43.0
