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| author | Richard Biener <rguenther@suse.de> | 2022-12-08 09:07:36 +0100 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2022-12-08 11:58:47 +0100 |
| commit | 892e8c520be37d0a0f14e2ae375103c5303ed549 (patch) | |
| tree | 8a8030495b65c9fdd64db3049263cf47e6f32b9c /gcc | |
| parent | 4505270128ef70538ea345f292e3eb85a5369eaf (diff) | |
| download | gcc-892e8c520be37d0a0f14e2ae375103c5303ed549.zip gcc-892e8c520be37d0a0f14e2ae375103c5303ed549.tar.gz gcc-892e8c520be37d0a0f14e2ae375103c5303ed549.tar.bz2 | |
tree-optimization/107699 - missed &data._M_elems + _1 != &data._M_elems folding
The following addresses a missed folding noticed in PR107699 that can
be fixed amending the existing &x + a != &x + b pattern to also handle
the case of only one side having a pointer plus. I'm moving the
patterns next to related simpifications showing there'd be an existing
pattern matching this if it were not gated with an explicit single_use
constraint. Note the new pattern also handles &x.a + a != &x.b, but
this hints at some unification / generalization opportunities here.
PR tree-optimization/107699
* match.pd (&a !=/== &a.b + c -> (&a - &a.b) !=/== c): New
pattern variant.
* gcc.dg/tree-ssa/pr107699.c: New testcase.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/match.pd | 21 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/pr107699.c | 15 |
2 files changed, 28 insertions, 8 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index f48cbd9..127cef9 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -2260,6 +2260,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) && (CONSTANT_CLASS_P (@1) || (single_use (@2) && single_use (@3)))) (op @1 { build_zero_cst (TREE_TYPE (@1)); })))) +/* (&a + b) !=/== (&a[1] + c) -> (&a[0] - &a[1]) + b !=/== c */ +(for neeq (ne eq) + (simplify + (neeq:c ADDR_EXPR@0 (pointer_plus ADDR_EXPR@2 @3)) + (with { poly_int64 diff; tree inner_type = TREE_TYPE (@3);} + (if (ptr_difference_const (@0, @2, &diff)) + (neeq { build_int_cst_type (inner_type, diff); } @3)))) + (simplify + (neeq (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3)) + (with { poly_int64 diff; tree inner_type = TREE_TYPE (@1);} + (if (ptr_difference_const (@0, @2, &diff)) + (neeq (plus { build_int_cst_type (inner_type, diff); } @1) @3))))) + /* X - Y < X is the same as Y > 0 when there is no overflow. For equality, this is also true with wrapping overflow. */ (for op (simple_comparison) @@ -2439,14 +2452,6 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (if (ptr_difference_const (@0, @2, &diff)) (plus { build_int_cst_type (type, diff); } (convert (minus @1 @3)))))) -/* (&a+b) !=/== (&a[1] + c) -> sizeof(a[0]) + b !=/== c */ -(for neeq (ne eq) - (simplify - (neeq (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3)) - (with { poly_int64 diff; tree inner_type = TREE_TYPE (@1);} - (if (ptr_difference_const (@0, @2, &diff)) - (neeq (plus { build_int_cst_type (inner_type, diff); } @1) @3))))) - /* Canonicalize (T *)(ptr - ptr-cst) to &MEM[ptr + -ptr-cst]. */ (simplify (convert (pointer_diff @0 INTEGER_CST@1)) diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr107699.c b/gcc/testsuite/gcc.dg/tree-ssa/pr107699.c new file mode 100644 index 0000000..4bf864d --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr107699.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-forwprop1" } */ + +struct { int data[16]; } x; + +int foo (int n) +{ + int *p = x.data + n; + /* Should simplify this to n * 4 != 0. */ + if ((void *)&x != (void *)p) + return 1; + return 0; +} + +/* { dg-final { scan-tree-dump " != 0" "forwprop1" } } */ |