From: Eric Botcazou <ebotca...@adacore.com>
Date: Sun, 04 Jun 2017 10:32:47 +0200
>> This is an attempt to fix PR target/80968. This bug has existed
>> basically forever.
>>
>> The stack_tie sequence seems to be how other targets deal with this
>> issue. I only emit this when alloca is used. If there are other
>> conditions that potentially would necessitate such a barrier, just let
>> me know.
>
> See my comment in the audit trail about the stack tie approach, let's just
> emit a frame_blockage instead.
That seems to work as well, following is going through a testsuite
run right now:
====================
[PATCH] sparc: Fix stack references in return delay slot.
gcc/
PR target/80968
* config/sparc/sparc.c (sparc_expand_prologue): Emit frame
blockage if function uses alloca.
gcc/testsuite/
* gcc.target/sparc/sparc-ret-3.c: New test.
---
gcc/config/sparc/sparc.c | 3 ++
gcc/testsuite/gcc.target/sparc/sparc-ret-3.c | 53 ++++++++++++++++++++++++++++
2 files changed, 56 insertions(+)
create mode 100644 gcc/testsuite/gcc.target/sparc/sparc-ret-3.c
diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 6dfb269..95a64a4 100644
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -5792,6 +5792,9 @@ sparc_expand_epilogue (bool for_eh)
{
HOST_WIDE_INT size = sparc_frame_size;
+ if (cfun->calls_alloca)
+ emit_insn (gen_frame_blockage ());
+
if (sparc_n_global_fp_regs > 0)
emit_save_or_restore_global_fp_regs (sparc_frame_base_reg,
sparc_frame_base_offset
diff --git a/gcc/testsuite/gcc.target/sparc/sparc-ret-3.c
b/gcc/testsuite/gcc.target/sparc/sparc-ret-3.c
new file mode 100644
index 0000000..7a151f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/sparc/sparc-ret-3.c
@@ -0,0 +1,53 @@
+/* PR target/80968 */
+/* { dg-do compile } */
+/* { dg-skip-if "no register windows" { *-*-* } { "-mflat" } { "" } } */
+/* { dg-require-effective-target ilp32 } */
+/* { dg-options "-mcpu=ultrasparc -O" } */
+
+/* Make sure references to the stack frame do not slip into the delay slot
+ of a return instruction. */
+
+struct crypto_shash {
+ unsigned int descsize;
+};
+struct crypto_shash *tfm;
+
+struct shash_desc {
+ struct crypto_shash *tfm;
+ unsigned int flags;
+
+ void *__ctx[] __attribute__((aligned(8)));
+};
+
+static inline unsigned int crypto_shash_descsize(struct crypto_shash *tfm)
+{
+ return tfm->descsize;
+}
+
+static inline void *shash_desc_ctx(struct shash_desc *desc)
+{
+ return desc->__ctx;
+}
+
+#define SHASH_DESC_ON_STACK(shash, ctx) \
+ char __##shash##_desc[sizeof(struct shash_desc) + \
+ crypto_shash_descsize(ctx)]
__attribute__((aligned(8))); \
+ struct shash_desc *shash = (struct shash_desc *)__##shash##_desc
+
+extern int crypto_shash_update(struct shash_desc *, const void *, unsigned
int);
+
+unsigned int bug(unsigned int crc, const void *address, unsigned int length)
+{
+ SHASH_DESC_ON_STACK(shash, tfm);
+ unsigned int *ctx = (unsigned int *)shash_desc_ctx(shash);
+ int err;
+
+ shash->tfm = tfm;
+ shash->flags = 0;
+ *ctx = crc;
+
+ err = crypto_shash_update(shash, address, length);
+
+ return *ctx;
+}
+/* { dg-final { scan-assembler "ld\[ \t\]*\\\[%i5\\+8\\\],
%i0\n\[^\n\]*return\[ \t\]*%i7\\+8" } } */
--
2.1.2.532.g19b5d50
