The C standard requires that, when initializing an aggregate, all
fieds not explicitly initialized shall be implicity zero-initialized
(more exactly "the same as objects that have static storage duration"
[6.7.9.21]).
Until now sparse didn't did this.
Fix this (when an initializer is present and the object not a scalar)
by first storing zeroes in the whole object before doing the
initialization of each fields explicitly initialized.
Note 1: this patch initialize the *whole* aggregate while the
standard only requires that existing fields are initialized.
Thanks to Linus to notice this.
Note 2: this implicit initialization is not needed if all fields are
explicitly initialized but is done anyway, for the moment.
Note 3: the code simplify nicely when there is a single field that is
initialized, much less so when there is several ones.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
linearize.c | 15 +++++
validation/linear/bitfield-init-zero.c | 102 ++++++++++++++++++++++++++++++++
validation/linear/struct-init-full.c | 28 +++++++++
validation/linear/struct-init-partial.c | 41 +++++++++++++
4 files changed, 186 insertions(+)
create mode 100644 validation/linear/bitfield-init-zero.c
create mode 100644 validation/linear/struct-init-full.c
create mode 100644 validation/linear/struct-init-partial.c
diff --git a/linearize.c b/linearize.c
index 5c273a91d..f628f5a74 100644
--- a/linearize.c
+++ b/linearize.c
@@ -1635,6 +1635,21 @@ static pseudo_t linearize_one_symbol(struct entrypoint *ep, struct symbol *sym)
sym->initialized = 1;
ad.address = symbol_pseudo(ep, sym);
+
+ if (sym->initializer && !is_scalar_type(sym)) {
+ // default zero initialization [6.7.9.21]
+ // FIXME: this init the whole aggregate while
+ // only the existing fields need to be initialized.
+ // FIXME: this init the whole aggregate even if
+ // all fields arelater explicitely initialized.
+ struct expression *expr = sym->initializer;
+ ad.pos = expr->pos;
+ ad.result_type = sym;
+ ad.source_type = base_type(sym);
+ ad.address = symbol_pseudo(ep, sym);
+ linearize_store_gen(ep, value_pseudo(0), &ad);
+ }
+
value = linearize_initializer(ep, sym->initializer, &ad);
finish_address_gen(ep, &ad);
return value;
diff --git a/validation/linear/bitfield-init-zero.c b/validation/linear/bitfield-init-zero.c
new file mode 100644
index 000000000..39a64345e
--- /dev/null
+++ b/validation/linear/bitfield-init-zero.c
@@ -0,0 +1,102 @@
+struct bfu {
+ unsigned int a:11;
+ unsigned int f:9;
+ unsigned int :2;
+ unsigned int z:3;
+};
+
+struct bfu bfuu_init(unsigned int a)
+{
+ struct bfu bf = { .f = a, };
+ return bf;
+}
+
+struct bfu bfus_init(int a)
+{
+ struct bfu bf = { .f = a, };
+ return bf;
+}
+
+unsigned int bfu_get0(void)
+{
+ struct bfu bf = { };
+ return bf.f;
+}
+
+
+struct bfs {
+ signed int a:11;
+ signed int f:9;
+ signed int :2;
+ signed int z:3;
+};
+
+struct bfs bfsu_init(unsigned int a)
+{
+ struct bfs bf = { .f = a, };
+ return bf;
+}
+
+struct bfs bfss_init(int a)
+{
+ struct bfs bf = { .f = a, };
+ return bf;
+}
+
+int bfs_get0(void)
+{
+ struct bfs bf = { };
+ return bf.f;
+}
+
+/*
+ * check-name: bitfield implicit init zero
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-start
+bfuu_init:
+.L0:
+ <entry-point>
+ cast.9 %r2 <- (32) %arg1
+ shl.32 %r4 <- %r2, $11
+ ret.32 %r4
+
+
+bfus_init:
+.L2:
+ <entry-point>
+ scast.9 %r10 <- (32) %arg1
+ shl.32 %r12 <- %r10, $11
+ ret.32 %r12
+
+
+bfu_get0:
+.L4:
+ <entry-point>
+ ret.32 $0
+
+
+bfsu_init:
+.L6:
+ <entry-point>
+ cast.9 %r23 <- (32) %arg1
+ shl.32 %r25 <- %r23, $11
+ ret.32 %r25
+
+
+bfss_init:
+.L8:
+ <entry-point>
+ scast.9 %r31 <- (32) %arg1
+ shl.32 %r33 <- %r31, $11
+ ret.32 %r33
+
+
+bfs_get0:
+.L10:
+ <entry-point>
+ ret.32 $0
+
+
+ * check-output-end
+ */
diff --git a/validation/linear/struct-init-full.c b/validation/linear/struct-init-full.c
new file mode 100644
index 000000000..f1b03db71
--- /dev/null
+++ b/validation/linear/struct-init-full.c
@@ -0,0 +1,28 @@
+struct s {
+ int a, b, c;
+};
+
+struct s s_init_all(int a)
+{
+ struct s s = { .a = a, .b = 42, .c = 123, };
+ return s;
+}
+
+/*
+ * check-name: struct implicit init zero not needed
+ * check-command: test-linearize -Wno-decl $file
+ * check-known-to-fail
+ *
+ * check-output-start
+s_init_all:
+.L4:
+ <entry-point>
+ store.32 %arg1 -> 0[s]
+ store.32 $42 -> 4[s]
+ store.32 $123 -> 8[s]
+ load.96 %r8 <- 0[s]
+ ret.96 %r8
+
+
+ * check-output-end
+ */
diff --git a/validation/linear/struct-init-partial.c b/validation/linear/struct-init-partial.c
new file mode 100644
index 000000000..1f5078bfa
--- /dev/null
+++ b/validation/linear/struct-init-partial.c
@@ -0,0 +1,41 @@
+struct s {
+ int a, b, c;
+};
+
+struct s s_init_first(int a)
+{
+ struct s s = { .a = a, };
+ return s;
+}
+
+struct s s_init_third(int a)
+{
+ struct s s = { .c = a, };
+ return s;
+}
+
+/*
+ * check-name: struct implicit init zero needed
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-start
+s_init_first:
+.L0:
+ <entry-point>
+ store.96 $0 -> 0[s]
+ store.32 %arg1 -> 0[s]
+ load.96 %r2 <- 0[s]
+ ret.96 %r2
+
+
+s_init_third:
+.L2:
+ <entry-point>
+ store.96 $0 -> 0[s]
+ store.32 %arg1 -> 8[s]
+ load.96 %r5 <- 0[s]
+ ret.96 %r5
+
+
+ * check-output-end
+ */
--
2.12.0
--
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