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| author | Richard Biener <rguenther@suse.de> | 2024-08-28 14:06:48 +0200 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2024-09-09 15:02:26 +0200 |
| commit | e7d5b9aa021f6fc32810670b18ffabe543262775 (patch) | |
| tree | f3340ad130b425003e3cc5f5d4f67c724c3eeafe | |
| parent | 898e3e95a6acf542baf03be95ce5bf7b3ad04276 (diff) | |
| download | gcc-e7d5b9aa021f6fc32810670b18ffabe543262775.zip gcc-e7d5b9aa021f6fc32810670b18ffabe543262775.tar.gz gcc-e7d5b9aa021f6fc32810670b18ffabe543262775.tar.bz2 | |
tree-optimization/116514 - handle pointer difference in bit-CCP
When evaluating the difference of two aligned pointers in CCP we
fail to handle the EXACT_DIV_EXPR by the element size that occurs.
The testcase then also exercises modulo to test alignment but
modulo by a power-of-two isn't handled either.
PR tree-optimization/116514
* tree-ssa-ccp.cc (bit_value_binop): Handle EXACT_DIV_EXPR
like TRUNC_DIV_EXPR. Handle exact division of a signed value
by a power-of-two like a shift. Handle unsigned division by
a power-of-two like a shift.
Handle unsigned TRUNC_MOD_EXPR by power-of-two, handle signed
TRUNC_MOD_EXPR by power-of-two if the result is zero.
* gcc.dg/tree-ssa/ssa-ccp-44.c: New testcase.
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-44.c | 13 | ||||
| -rw-r--r-- | gcc/tree-ssa-ccp.cc | 27 |
2 files changed, 39 insertions, 1 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-44.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-44.c new file mode 100644 index 0000000..f1f09bf --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-44.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-ccp1" } */ + +int +test(int* a, int* b) +{ + __INTPTR_TYPE__ delta = (int*)__builtin_assume_aligned(b, 32) + - (int*)__builtin_assume_aligned(a, 32); + __INTPTR_TYPE__ x = delta % 8; + return (x == 0); +} + +/* { dg-final { scan-tree-dump "return 1;" "ccp1" } } */ diff --git a/gcc/tree-ssa-ccp.cc b/gcc/tree-ssa-ccp.cc index 47b2ce9..a5f6ef5 100644 --- a/gcc/tree-ssa-ccp.cc +++ b/gcc/tree-ssa-ccp.cc @@ -1921,6 +1921,27 @@ bit_value_binop (enum tree_code code, signop sgn, int width, { widest_int r1max = r1val | r1mask; widest_int r2max = r2val | r2mask; + if (r2mask == 0) + { + widest_int shift = wi::exact_log2 (r2val); + if (shift != -1) + { + // Handle modulo by a power of 2 as a bitwise and. + widest_int tem_val, tem_mask; + bit_value_binop (BIT_AND_EXPR, sgn, width, &tem_val, &tem_mask, + r1type_sgn, r1type_precision, r1val, r1mask, + r2type_sgn, r2type_precision, + r2val - 1, r2mask); + if (sgn == UNSIGNED + || !wi::neg_p (r1max) + || (tem_mask == 0 && tem_val == 0)) + { + *val = tem_val; + *mask = tem_mask; + return; + } + } + } if (sgn == UNSIGNED || (!wi::neg_p (r1max) && !wi::neg_p (r2max))) { @@ -1949,11 +1970,15 @@ bit_value_binop (enum tree_code code, signop sgn, int width, } break; + case EXACT_DIV_EXPR: case TRUNC_DIV_EXPR: { widest_int r1max = r1val | r1mask; widest_int r2max = r2val | r2mask; - if (r2mask == 0 && !wi::neg_p (r1max)) + if (r2mask == 0 + && (code == EXACT_DIV_EXPR + || sgn == UNSIGNED + || !wi::neg_p (r1max))) { widest_int shift = wi::exact_log2 (r2val); if (shift != -1) |