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| author | Hans-Peter Nilsson <hp@axis.com> | 2020-08-13 05:12:23 +0200 |
|---|---|---|
| committer | Giuliano Belinassi <giuliano.belinassi@usp.br> | 2020-08-17 15:08:08 -0300 |
| commit | 7143ab0282e7ed1c159d3c7b8d9edece38594521 (patch) | |
| tree | bc8152759aba1be2e53e07f679a6068e58ecb959 | |
| parent | 9231e2be51f5ed01919d414fbd7570f6687fdd62 (diff) | |
| download | gcc-7143ab0282e7ed1c159d3c7b8d9edece38594521.zip gcc-7143ab0282e7ed1c159d3c7b8d9edece38594521.tar.gz gcc-7143ab0282e7ed1c159d3c7b8d9edece38594521.tar.bz2 | |
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.c | 2 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr94600-6.c | 2 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr94600-7.c | 2 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr94600-8.c | 2 |
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) |