The function address_taken() check that the address of a variable
is not used for anything else than for doing a memory access.
If the function fails, it means that the address can escape and
thus can be used to modify the variable indirectly and the
memop simplification would then be unsafe.
The function do this check by assuming that any uses by an instruction
other than a load or a store can escape the address, which is true.
However it doesn't take in account that if the variable's address is
used, not as the address of a store, but as the value stored, then
this address also escape.
Fix this by adding a check that the use of the variable's address
is effectively done as the address of stores & loads and not as
the value stored by the memop.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
memops.c | 2 ++
validation/mem2reg/address-used00.c | 1 -
validation/optim/address-used01.c | 19 +++++++++++++++++++
3 files changed, 21 insertions(+), 1 deletion(-)
create mode 100644 validation/optim/address-used01.c
diff --git a/memops.c b/memops.c
index 5762f4f2c..30316391e 100644
--- a/memops.c
+++ b/memops.c
@@ -69,6 +69,8 @@ static int address_taken(pseudo_t pseudo)
struct instruction *insn = pu->insn;
if (insn->bb && (insn->opcode != OP_LOAD && insn->opcode != OP_STORE))
return 1;
+ if (pu->userp != &insn->src)
+ return 1;
} END_FOR_EACH_PTR(pu);
return 0;
}
diff --git a/validation/mem2reg/address-used00.c b/validation/mem2reg/address-used00.c
index f2d6c87bd..1501bc1ca 100644
--- a/validation/mem2reg/address-used00.c
+++ b/validation/mem2reg/address-used00.c
@@ -13,7 +13,6 @@ int foo(int **g, int j)
/*
* check-name: address-used00
* check-command: test-linearize -Wno-decl -fdump-ir=final $file
- * check-known-to-fail
* check-output-ignore
* check-output-excludes: ret\\..* \\$1
*/
diff --git a/validation/optim/address-used01.c b/validation/optim/address-used01.c
new file mode 100644
index 000000000..6ca75ffe5
--- /dev/null
+++ b/validation/optim/address-used01.c
@@ -0,0 +1,19 @@
+int foo(int **g, int j)
+{
+ int i = 1;
+ int *a;
+ int **p;
+
+ a = &i;
+ p = &a;
+ *p[0] = 0;
+ return i;
+}
+
+/*
+ * check-name: address-used01
+ * check-command: test-linearize -Wno-decl -fdump-ir=final $file
+ * check-known-to-fail
+ * check-output-ignore
+ * check-output-contains: ret\\..* \\$0
+ */
--
2.16.2
--
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