From 4b2c06f49f8d7365e2aa15f32cbc6a726c9ff9fb Mon Sep 17 00:00:00 2001 From: Kyrylo Tkachov Date: Wed, 2 Nov 2016 09:28:35 +0000 Subject: [PATCH] PR tree-optimization/78170: Truncate sign-extended padding when encoding bitfields PR tree-optimization/78170 * gimple-ssa-store-merging.c (encode_tree_to_bitpos): Truncate padding introduced by native_encode_expr on little-endian as well. * gcc.c-torture/execute/pr78170.c: New test. From-SVN: r241779 --- gcc/ChangeLog | 6 +++ gcc/gimple-ssa-store-merging.c | 18 +++++++-- gcc/testsuite/ChangeLog | 5 +++ gcc/testsuite/gcc.c-torture/execute/pr78170.c | 37 +++++++++++++++++++ 4 files changed, 62 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr78170.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index aee2b83f8b3..ba76566850d 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2016-11-02 Kyrylo Tkachov + + PR tree-optimization/78170 + * gimple-ssa-store-merging.c (encode_tree_to_bitpos): Truncate padding + introduced by native_encode_expr on little-endian as well. + 2016-11-02 Kyrylo Tkachov PR tree-optimization/78162 diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c index feba907559f..f279511e1c6 100644 --- a/gcc/gimple-ssa-store-merging.c +++ b/gcc/gimple-ssa-store-merging.c @@ -432,13 +432,23 @@ encode_tree_to_bitpos (tree expr, unsigned char *ptr, int bitlen, int bitpos, contain a sign bit due to sign-extension). */ unsigned int padding = byte_size - ROUND_UP (bitlen, BITS_PER_UNIT) / BITS_PER_UNIT - 1; - if (BYTES_BIG_ENDIAN) + if (padding != 0) { - tmpbuf += padding; + /* On big-endian the padding is at the 'front' so just skip the initial + bytes. */ + if (BYTES_BIG_ENDIAN) + tmpbuf += padding; + byte_size -= padding; if (bitlen % BITS_PER_UNIT != 0) - clear_bit_region_be (tmpbuf, BITS_PER_UNIT - 1, - BITS_PER_UNIT - (bitlen % BITS_PER_UNIT)); + { + if (BYTES_BIG_ENDIAN) + clear_bit_region_be (tmpbuf, BITS_PER_UNIT - 1, + BITS_PER_UNIT - (bitlen % BITS_PER_UNIT)); + else + clear_bit_region (tmpbuf, bitlen, + byte_size * BITS_PER_UNIT - bitlen); + } } /* Clear the bit region in PTR where the bits from TMPBUF will be diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index d979a56fcf7..c06c315821e 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2016-11-02 Kyrylo Tkachov + + PR tree-optimization/78170 + * gcc.c-torture/execute/pr78170.c: New test. + 2016-11-02 Kyrylo Tkachov PR tree-optimization/78162 diff --git a/gcc/testsuite/gcc.c-torture/execute/pr78170.c b/gcc/testsuite/gcc.c-torture/execute/pr78170.c new file mode 100644 index 00000000000..8ef812ee6ac --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/execute/pr78170.c @@ -0,0 +1,37 @@ +/* PR tree-optimization/78170. + Check that sign-extended store to a bitfield + doesn't overwrite other fields. */ + +int a, b, d; + +struct S0 +{ + int f0; + int f1; + int f2; + int f3; + int f4; + int f5:15; + int f6:17; + int f7:2; + int f8:30; +} c; + +void fn1 () +{ + d = b = 1; + for (; b; b = a) + { + struct S0 e = { 0, 0, 0, 0, 0, 0, 1, 0, 1 }; + c = e; + c.f6 = -1; + } +} + +int main () +{ + fn1 (); + if (c.f7 != 0) + __builtin_abort (); + return 0; +} -- 2.30.2