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| author | Aldy Hernandez <aldyh@redhat.com> | 2021-10-01 13:05:36 +0200 |
|---|---|---|
| committer | Aldy Hernandez <aldyh@redhat.com> | 2021-10-02 00:03:23 +0200 |
| commit | 5f9ccf17de7f7581412c6bffd4a37beca9a79836 (patch) | |
| tree | e10e84c7a9062a57145cea3cbd6229b47a350446 /gcc | |
| parent | 257d2890a769a8aa564d079170377e637e07acb1 (diff) | |
| download | gcc-5f9ccf17de7f7581412c6bffd4a37beca9a79836.zip gcc-5f9ccf17de7f7581412c6bffd4a37beca9a79836.tar.gz gcc-5f9ccf17de7f7581412c6bffd4a37beca9a79836.tar.bz2 | |
[PR102546] X << Y being non-zero implies X is also non-zero.
This patch teaches this to range-ops.
Tested on x86-64 Linux.
gcc/ChangeLog:
PR tree-optimization/102546
* range-op.cc (operator_lshift::op1_range): Teach range-ops that
X << Y is non-zero implies X is also non-zero.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/range-op.cc | 18 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/pr102546.c | 23 |
2 files changed, 37 insertions, 4 deletions
diff --git a/gcc/range-op.cc b/gcc/range-op.cc index 5e37133..2baca4a 100644 --- a/gcc/range-op.cc +++ b/gcc/range-op.cc @@ -2078,6 +2078,12 @@ operator_lshift::op1_range (irange &r, relation_kind rel ATTRIBUTE_UNUSED) const { tree shift_amount; + + if (!lhs.contains_p (build_zero_cst (type))) + r.set_nonzero (type); + else + r.set_varying (type); + if (op2.singleton_p (&shift_amount)) { wide_int shift = wi::to_wide (shift_amount); @@ -2089,21 +2095,24 @@ operator_lshift::op1_range (irange &r, return false; if (shift == 0) { - r = lhs; + r.intersect (lhs); return true; } // Work completely in unsigned mode to start. tree utype = type; + int_range_max tmp_range; if (TYPE_SIGN (type) == SIGNED) { int_range_max tmp = lhs; utype = unsigned_type_for (type); range_cast (tmp, utype); - op_rshift.fold_range (r, utype, tmp, op2); + op_rshift.fold_range (tmp_range, utype, tmp, op2); } else - op_rshift.fold_range (r, utype, lhs, op2); + op_rshift.fold_range (tmp_range, utype, lhs, op2); + + r.intersect (tmp_range); // Start with ranges which can produce the LHS by right shifting the // result by the shift amount. @@ -2128,7 +2137,8 @@ operator_lshift::op1_range (irange &r, range_cast (r, type); return true; } - return false; + + return !r.varying_p (); } bool diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c new file mode 100644 index 0000000..4bd9874 --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr102546.c @@ -0,0 +1,23 @@ +// { dg-do compile } +// { dg-options "-O3 -fdump-tree-optimized" } + +static int a; +static char b, c, d; +void bar(void); +void foo(void); + +int main() { + int f = 0; + for (; f <= 5; f++) { + bar(); + b = b && f; + d = f << f; + if (!(a >= d || f)) + foo(); + c = 1; + for (; c; c = 0) + ; + } +} + +// { dg-final { scan-tree-dump-not "foo" "optimized" } } |