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authorHans-Peter Nilsson <hp@axis.com>2020-08-13 05:12:23 +0200
committerHans-Peter Nilsson <hp@axis.com>2020-08-13 05:12:23 +0200
commit5db1fa9bc69dd58ce2f93dd707d05efcfe89ffa8 (patch)
tree921daa492fa48b5dcc4d39222c47b353c963cd1a
parent2ec803e768a820c9208fea2e8b144ee359379139 (diff)
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gcc.dg/pr94600-5.c .. -8.c: Align struct t0 explictly, as a type, PR middle-end/94600
The bitfield-struct t0 in gcc.dg/pr94600-1.c ..-4.c is assigned to a pointer that is a (volatile-and-pointer-)cast literal, so gcc doesn't need to be otherwise told that the address is aligned. But, variants pr94600-5.c ..-8.c are assigned through a "volatile t0 *", and rely on the *type* being naturally aligned, or that the machine has non-strict-alignment moves. Unfortunately, systems exist (for some definitions of exist) where such structs aren't always naturally aligned, for example if it contains only (small) bitfields, even though the size is a naturally accessible size. Specifically, the mmix-knuth-mmixware port has only *byte* alignment for this struct. (If an int is added to the struct, alignment is promoted.) IOW, a prerequisite of the test is false: the struct doesn't have the same alignment as an integer of the same size. The effect is assignment in byte-size pieces, and the test fails. (For a non-volatile assignment, memcpy is called.) That's easily fixable by defining the type as having a specific alignment. This is also closer to the type in the original code, and also as the first variants aren't affected, no second thought or re-visit of pre-fixed compiler is needed. I don't plan to back-port this to gcc-10 branch however. I did sanity-check that the tests still pass on ppc64le-linux. gcc/testsuite: PR middle-end/94600 * gcc.dg/pr94600-5.c, gcc.dg/pr94600-6.c, gcc.dg/pr94600-7.c, gcc.dg/pr94600-8.c: Align t0 to 4-byte boundary.
-rw-r--r--gcc/testsuite/gcc.dg/pr94600-5.c2
-rw-r--r--gcc/testsuite/gcc.dg/pr94600-6.c2
-rw-r--r--gcc/testsuite/gcc.dg/pr94600-7.c2
-rw-r--r--gcc/testsuite/gcc.dg/pr94600-8.c2
4 files changed, 4 insertions, 4 deletions
diff --git a/gcc/testsuite/gcc.dg/pr94600-5.c b/gcc/testsuite/gcc.dg/pr94600-5.c
index 90085b3..3be0249 100644
--- a/gcc/testsuite/gcc.dg/pr94600-5.c
+++ b/gcc/testsuite/gcc.dg/pr94600-5.c
@@ -9,7 +9,7 @@ typedef struct {
unsigned int f1 : 11;
unsigned int f2 : 10;
unsigned int f3 : 7;
-} t0;
+} t0 __attribute__((__aligned__(4)));
static t0 a0[] = {
{ .f0 = 7, .f1 = 99, .f3 = 1, },
diff --git a/gcc/testsuite/gcc.dg/pr94600-6.c b/gcc/testsuite/gcc.dg/pr94600-6.c
index 23a81a0..c247afe 100644
--- a/gcc/testsuite/gcc.dg/pr94600-6.c
+++ b/gcc/testsuite/gcc.dg/pr94600-6.c
@@ -9,7 +9,7 @@ typedef struct {
unsigned int f1 : 11;
unsigned int f2 : 10;
unsigned int f3 : 7;
-} t0;
+} t0 __attribute__((__aligned__(4)));
void
bar(volatile t0 *b)
diff --git a/gcc/testsuite/gcc.dg/pr94600-7.c b/gcc/testsuite/gcc.dg/pr94600-7.c
index 2f5c759..81c5231 100644
--- a/gcc/testsuite/gcc.dg/pr94600-7.c
+++ b/gcc/testsuite/gcc.dg/pr94600-7.c
@@ -9,7 +9,7 @@ typedef struct {
unsigned int f1 : 11;
unsigned int f2 : 10;
unsigned int f3 : 7;
-} t0;
+} t0 __attribute__((__aligned__(4)));
static t0 a0[] = {
{ .f0 = 7, .f1 = 99, .f3 = 1, },
diff --git a/gcc/testsuite/gcc.dg/pr94600-8.c b/gcc/testsuite/gcc.dg/pr94600-8.c
index ded814b..201b2add4 100644
--- a/gcc/testsuite/gcc.dg/pr94600-8.c
+++ b/gcc/testsuite/gcc.dg/pr94600-8.c
@@ -9,7 +9,7 @@ typedef struct {
unsigned int f1 : 11;
unsigned int f2 : 10;
unsigned int f3 : 7;
-} t0;
+} t0 __attribute__((__aligned__(4)));
void
bar(volatile t0 *b)