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| author | glisse <glisse@138bc75d-0d04-0410-961f-82ee72b054a4> | 2016-04-27 21:30:27 +0000 |
|---|---|---|
| committer | glisse <glisse@138bc75d-0d04-0410-961f-82ee72b054a4> | 2016-04-27 21:30:27 +0000 |
| commit | dfba09056728a3d14c8bfb4462c3444e023d969b (patch) | |
| tree | ccdf4790df4f3d8e0acf455f0f824154385e9461 /gcc/match.pd | |
| parent | e3008af501a77da4e9b4b5102d25066427eae376 (diff) | |
| download | gcc-dfba09056728a3d14c8bfb4462c3444e023d969b.tar.gz | |
match.pd: unsigned A - B > A --> A < B
2016-04-27 Marc Glisse <marc.glisse@inria.fr>
gcc/
* match.pd (A - B > A, A + B < A): New transformations.
gcc/testsuite/
* gcc.dg/tree-ssa/overflow-2.c: New testcase.
* gcc.dg/tree-ssa/minus-ovf.c: Likewise.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@235537 138bc75d-0d04-0410-961f-82ee72b054a4
Diffstat (limited to 'gcc/match.pd')
| -rw-r--r-- | gcc/match.pd | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index 476818709cf..f645157a4f4 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -2508,6 +2508,60 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (out @0 { wide_int_to_tree (TREE_TYPE (@0), wi::max_value (TYPE_PRECISION (TREE_TYPE (@0)), UNSIGNED) - @1); })))) +/* To detect overflow in unsigned A - B, A < B is simpler than A - B > A. + However, the detection logic for SUB_OVERFLOW in tree-ssa-math-opts.c + expects the long form, so we restrict the transformation for now. */ +(for cmp (gt le) + (simplify + (cmp (minus@2 @0 @1) @0) + (if (single_use (@2) + && ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && TYPE_UNSIGNED (TREE_TYPE (@0)) + && TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))) + (cmp @1 @0)))) +(for cmp (lt ge) + (simplify + (cmp @0 (minus@2 @0 @1)) + (if (single_use (@2) + && ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)) + && TYPE_UNSIGNED (TREE_TYPE (@0)) + && TYPE_OVERFLOW_WRAPS (TREE_TYPE (@0))) + (cmp @0 @1)))) + +/* Testing for overflow is unnecessary if we already know the result. */ +/* A < A - B */ +(for cmp (lt ge) + out (ne eq) + (simplify + (cmp @0 (realpart (IFN_SUB_OVERFLOW@2 @0 @1))) + (if (TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (out (imagpart @2) { build_zero_cst (TREE_TYPE (@0)); })))) +/* A - B > A */ +(for cmp (gt le) + out (ne eq) + (simplify + (cmp (realpart (IFN_SUB_OVERFLOW@2 @0 @1)) @0) + (if (TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (out (imagpart @2) { build_zero_cst (TREE_TYPE (@0)); })))) +/* A + B < A */ +(for cmp (lt ge) + out (ne eq) + (simplify + (cmp (realpart (IFN_ADD_OVERFLOW:c@2 @0 @1)) @0) + (if (TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (out (imagpart @2) { build_zero_cst (TREE_TYPE (@0)); })))) +/* A > A + B */ +(for cmp (gt le) + out (ne eq) + (simplify + (cmp @0 (realpart (IFN_ADD_OVERFLOW:c@2 @0 @1))) + (if (TYPE_UNSIGNED (TREE_TYPE (@0)) + && types_match (TREE_TYPE (@0), TREE_TYPE (@1))) + (out (imagpart @2) { build_zero_cst (TREE_TYPE (@0)); })))) + /* Simplification of math builtins. These rules must all be optimizations as well as IL simplifications. If there is a possibility that the new |