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| author | Bin Cheng <bin.cheng@arm.com> | 2017-01-24 13:09:27 +0000 |
|---|---|---|
| committer | Bin Cheng <amker@gcc.gnu.org> | 2017-01-24 13:09:27 +0000 |
| commit | cf8d19de268ebcd25bb6e917ff16ee286d96dedd (patch) | |
| tree | 33da9dab32cb1102151fce01f63a0a6c3ff22f24 /gcc/tree-ssa-loop-niter.c | |
| parent | 5fd1486ce58297190c2b924e96e716087139a8b5 (diff) | |
| download | gcc-cf8d19de268ebcd25bb6e917ff16ee286d96dedd.zip gcc-cf8d19de268ebcd25bb6e917ff16ee286d96dedd.tar.gz gcc-cf8d19de268ebcd25bb6e917ff16ee286d96dedd.tar.bz2 | |
re PR tree-optimization/79159 (spurious array-bounds warning)
PR tree-optimization/79159
* tree-ssa-loop-niter.c (get_cst_init_from_scev): New function.
(record_nonwrapping_iv): Imporve boundary using above function if no
value range information.
gcc/testsuite
PR tree-optimization/79159
* g++.dg/tree-ssa/pr79159.C: New test.
From-SVN: r244868
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 43 |
1 files changed, 41 insertions, 2 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 8328625..efcf3ed 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -3059,6 +3059,43 @@ record_control_iv (struct loop *loop, struct tree_niter_desc *niter) return; } +/* This function returns TRUE if below conditions are satisfied: + 1) VAR is SSA variable. + 2) VAR is an IV:{base, step} in its defining loop. + 3) IV doesn't overflow. + 4) Both base and step are integer constants. + 5) Base is the MIN/MAX value depends on IS_MIN. + Store value of base to INIT correspondingly. */ + +static bool +get_cst_init_from_scev (tree var, wide_int *init, bool is_min) +{ + if (TREE_CODE (var) != SSA_NAME) + return false; + + gimple *def_stmt = SSA_NAME_DEF_STMT (var); + struct loop *loop = loop_containing_stmt (def_stmt); + + if (loop == NULL) + return false; + + affine_iv iv; + if (!simple_iv (loop, loop, var, &iv, false)) + return false; + + if (!iv.no_overflow) + return false; + + if (TREE_CODE (iv.base) != INTEGER_CST || TREE_CODE (iv.step) != INTEGER_CST) + return false; + + if (is_min == tree_int_cst_sign_bit (iv.step)) + return false; + + *init = iv.base; + return true; +} + /* Record the estimate on number of iterations of LOOP based on the fact that the induction variable BASE + STEP * i evaluated in STMT does not wrap and its values belong to the range <LOW, HIGH>. REALISTIC is true if the @@ -3100,7 +3137,8 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple *stmt, if (TREE_CODE (orig_base) == SSA_NAME && TREE_CODE (high) == INTEGER_CST && INTEGRAL_TYPE_P (TREE_TYPE (orig_base)) - && get_range_info (orig_base, &min, &max) == VR_RANGE + && (get_range_info (orig_base, &min, &max) == VR_RANGE + || get_cst_init_from_scev (orig_base, &max, false)) && wi::gts_p (high, max)) base = wide_int_to_tree (unsigned_type, max); else if (TREE_CODE (base) != INTEGER_CST @@ -3117,7 +3155,8 @@ record_nonwrapping_iv (struct loop *loop, tree base, tree step, gimple *stmt, if (TREE_CODE (orig_base) == SSA_NAME && TREE_CODE (low) == INTEGER_CST && INTEGRAL_TYPE_P (TREE_TYPE (orig_base)) - && get_range_info (orig_base, &min, &max) == VR_RANGE + && (get_range_info (orig_base, &min, &max) == VR_RANGE + || get_cst_init_from_scev (orig_base, &min, true)) && wi::gts_p (min, low)) base = wide_int_to_tree (unsigned_type, min); else if (TREE_CODE (base) != INTEGER_CST |