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| author | Jakub Jelinek <jakub@redhat.com> | 2020-01-30 21:28:17 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2020-01-30 21:28:17 +0100 |
| commit | 56b92750f83724177d2c6eae30c208e935a56a37 (patch) | |
| tree | 4442d994ad2a140f6904ede7a42d02c80a07ddcc /gcc | |
| parent | 4dd468a042e19ef0fdbb1c53ca4060d4cb4972c5 (diff) | |
| download | gcc-56b92750f83724177d2c6eae30c208e935a56a37.zip gcc-56b92750f83724177d2c6eae30c208e935a56a37.tar.gz gcc-56b92750f83724177d2c6eae30c208e935a56a37.tar.bz2 | |
combine: Punt on out of range rotate counts [PR93505]
What happens on this testcase is with the out of bounds rotate we get:
Trying 13 -> 16:
13: r129:SI=r132:DI#0<-<0x20
REG_DEAD r132:DI
16: r123:DI=r129:SI<0
REG_DEAD r129:SI
Successfully matched this instruction:
(set (reg/v:DI 123 [ <retval> ])
(const_int 0 [0]))
during combine. So, perhaps we could also change simplify-rtx.c to punt
if it is out of bounds rather than trying to optimize anything.
Or, but probably GCC11 material, if we decide that ROTATE/ROTATERT doesn't
have out of bounds counts or introduce targetm.rotate_truncation_mask,
we should truncate the argument instead of punting.
Punting is better for backports though.
2020-01-30 Jakub Jelinek <jakub@redhat.com>
PR middle-end/93505
* combine.c (simplify_comparison) <case ROTATE>: Punt on out of range
rotate counts.
* gcc.c-torture/compile/pr93505.c: New test.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 6 | ||||
| -rw-r--r-- | gcc/combine.c | 3 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.c-torture/compile/pr93505.c | 15 |
4 files changed, 28 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 7132bf0..f2cc027 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2020-01-30 Jakub Jelinek <jakub@redhat.com> + + PR middle-end/93505 + * combine.c (simplify_comparison) <case ROTATE>: Punt on out of range + rotate counts. + 2020-01-30 Andrew Stubbs <ams@codesourcery.com> * config/gcn/gcn.c (print_operand): Handle LTGT. diff --git a/gcc/combine.c b/gcc/combine.c index 0272e75..d44b9c3 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -12410,7 +12410,8 @@ simplify_comparison (enum rtx_code code, rtx *pop0, rtx *pop1) bit. This will be converted into a ZERO_EXTRACT. */ if (const_op == 0 && sign_bit_comparison_p && CONST_INT_P (XEXP (op0, 1)) - && mode_width <= HOST_BITS_PER_WIDE_INT) + && mode_width <= HOST_BITS_PER_WIDE_INT + && UINTVAL (XEXP (op0, 1)) < mode_width) { op0 = simplify_and_const_int (NULL_RTX, mode, XEXP (op0, 0), (HOST_WIDE_INT_1U diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 269adb2..ce53e2c 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2020-01-30 Jakub Jelinek <jakub@redhat.com> + + PR middle-end/93505 + * gcc.c-torture/compile/pr93505.c: New test. + 2020-01-30 Jeff Law <law@redhat.com * gcc.dg/tree-ssa/ssa-dse-26.c: Make existing dg-final scan diff --git a/gcc/testsuite/gcc.c-torture/compile/pr93505.c b/gcc/testsuite/gcc.c-torture/compile/pr93505.c new file mode 100644 index 0000000..0627962 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr93505.c @@ -0,0 +1,15 @@ +/* PR middle-end/93505 */ + +unsigned a; + +unsigned +foo (unsigned x) +{ + unsigned int y = 32 - __builtin_bswap64 (-a); + /* This would be UB (x << 32) at runtime. Ensure we don't + invoke UB in the compiler because of that (visible with + bootstrap-ubsan). */ + x = x << y | x >> (-y & 31); + x >>= 31; + return x; +} |