This makes sure to put special-ops expanded rhs left where expression rewrite expects it.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed. 2020-08-27 Richard Biener <rguent...@suse.de> PR tree-optimization/96579 * tree-ssa-reassoc.c (linearize_expr_tree): If we expand rhs via special ops make sure to swap operands. * gcc.dg/pr96579.c: New testcase. --- gcc/testsuite/gcc.dg/pr96579.c | 4 ++++ gcc/tree-ssa-reassoc.c | 13 +++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr96579.c diff --git a/gcc/testsuite/gcc.dg/pr96579.c b/gcc/testsuite/gcc.dg/pr96579.c new file mode 100644 index 00000000000..49fdcb40359 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr96579.c @@ -0,0 +1,4 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fno-tree-forwprop -ffast-math -fno-tree-vrp" } */ + +#include "pr96370.c" diff --git a/gcc/tree-ssa-reassoc.c b/gcc/tree-ssa-reassoc.c index fed463b0350..a5f5d52edab 100644 --- a/gcc/tree-ssa-reassoc.c +++ b/gcc/tree-ssa-reassoc.c @@ -5651,13 +5651,20 @@ linearize_expr_tree (vec<operand_entry *> *ops, gimple *stmt, if (!binrhsisreassoc) { - if (!try_special_add_to_ops (ops, rhscode, binrhs, binrhsdef)) + bool swap = false; + if (try_special_add_to_ops (ops, rhscode, binrhs, binrhsdef)) + /* If we add ops for the rhs we expect to be able to recurse + to it via the lhs during expression rewrite so swap + operands. */ + swap = true; + else add_to_ops_vec (ops, binrhs); if (!try_special_add_to_ops (ops, rhscode, binlhs, binlhsdef)) add_to_ops_vec (ops, binlhs); - return; + if (!swap) + return; } if (dump_file && (dump_flags & TDF_DETAILS)) @@ -5676,6 +5683,8 @@ linearize_expr_tree (vec<operand_entry *> *ops, gimple *stmt, fprintf (dump_file, " is now "); print_gimple_stmt (dump_file, stmt, 0); } + if (!binrhsisreassoc) + return; /* We want to make it so the lhs is always the reassociative op, so swap. */ -- 2.26.2