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| author | Richard Biener <rguenther@suse.de> | 2018-11-08 08:03:12 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2018-11-08 08:03:12 +0000 |
| commit | 85eaf6c6a3678d7eb19552a8a6f58018e6892115 (patch) | |
| tree | 2f0c0aea397f54e0dbf30d9a6eb61dbb6c78dd07 /gcc/tree-ssa-phiopt.c | |
| parent | ab6813850d0a51f90f57a0e4da470cb0b5c5b1f3 (diff) | |
| download | gcc-85eaf6c6a3678d7eb19552a8a6f58018e6892115.zip gcc-85eaf6c6a3678d7eb19552a8a6f58018e6892115.tar.gz gcc-85eaf6c6a3678d7eb19552a8a6f58018e6892115.tar.bz2 | |
re PR target/87913 (max(n, 1) code generation)
2018-11-08 Richard Biener <rguenther@suse.de>
PR tree-optimization/87913
* tree-ssa-phiopt.c (minmax_replacement): Turn EQ/NE compares
of extreme values to ordered comparisons.
* gcc.dg/tree-ssa/phi-opt-20.c: New testcase.
From-SVN: r265909
Diffstat (limited to 'gcc/tree-ssa-phiopt.c')
| -rw-r--r-- | gcc/tree-ssa-phiopt.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/gcc/tree-ssa-phiopt.c b/gcc/tree-ssa-phiopt.c index 0784510..64039e2 100644 --- a/gcc/tree-ssa-phiopt.c +++ b/gcc/tree-ssa-phiopt.c @@ -1204,7 +1204,7 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, edge e0, edge e1, gimple *phi, tree arg0, tree arg1) { - tree result, type; + tree result, type, rhs; gcond *cond; gassign *new_stmt; edge true_edge, false_edge; @@ -1220,6 +1220,25 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, cond = as_a <gcond *> (last_stmt (cond_bb)); cmp = gimple_cond_code (cond); + rhs = gimple_cond_rhs (cond); + + /* Turn EQ/NE of extreme values to order comparisons. */ + if ((cmp == NE_EXPR || cmp == EQ_EXPR) + && TREE_CODE (rhs) == INTEGER_CST) + { + if (wi::eq_p (wi::to_wide (rhs), wi::min_value (TREE_TYPE (rhs)))) + { + cmp = (cmp == EQ_EXPR) ? LT_EXPR : GE_EXPR; + rhs = wide_int_to_tree (TREE_TYPE (rhs), + wi::min_value (TREE_TYPE (rhs)) + 1); + } + else if (wi::eq_p (wi::to_wide (rhs), wi::max_value (TREE_TYPE (rhs)))) + { + cmp = (cmp == EQ_EXPR) ? GT_EXPR : LE_EXPR; + rhs = wide_int_to_tree (TREE_TYPE (rhs), + wi::max_value (TREE_TYPE (rhs)) - 1); + } + } /* This transformation is only valid for order comparisons. Record which operand is smaller/larger if the result of the comparison is true. */ @@ -1228,7 +1247,7 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, if (cmp == LT_EXPR || cmp == LE_EXPR) { smaller = gimple_cond_lhs (cond); - larger = gimple_cond_rhs (cond); + larger = rhs; /* If we have smaller < CST it is equivalent to smaller <= CST-1. Likewise smaller <= CST is equivalent to smaller < CST+1. */ if (TREE_CODE (larger) == INTEGER_CST) @@ -1255,7 +1274,7 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb, } else if (cmp == GT_EXPR || cmp == GE_EXPR) { - smaller = gimple_cond_rhs (cond); + smaller = rhs; larger = gimple_cond_lhs (cond); /* If we have larger > CST it is equivalent to larger >= CST+1. Likewise larger >= CST is equivalent to larger > CST-1. */ |