From 1a0bce98dcf84dd0a7b3ac67b51ac68758cc7ad0 Mon Sep 17 00:00:00 2001 From: Tamar Christina Date: Thu, 18 Nov 2021 11:22:11 +0000 Subject: [PATCH] middle-end: Fix FMA detection when inspecting gimple which have no LHS. convert_mult_to_fma assumes that all gimple_assigns have a LHS set. This assumption is however not true when an IFN is kept around just for the side-effects. In those situations you have just the IFN and lhs will be null. Since there's no LHS, there also can't be any ADD and such it can't be an FMA so it's correct to just return early if no LHS. gcc/ChangeLog: PR tree-optimization/103253 * tree-ssa-math-opts.c (convert_mult_to_fma): Check for LHS. gcc/testsuite/ChangeLog: PR tree-optimization/103253 * gcc.dg/vect/pr103253.c: New test. --- gcc/testsuite/gcc.dg/vect/pr103253.c | 16 ++++++++++++++++ gcc/tree-ssa-math-opts.c | 4 ++++ 2 files changed, 20 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/vect/pr103253.c diff --git a/gcc/testsuite/gcc.dg/vect/pr103253.c b/gcc/testsuite/gcc.dg/vect/pr103253.c new file mode 100644 index 0000000..abe3f09 --- /dev/null +++ b/gcc/testsuite/gcc.dg/vect/pr103253.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target fopenmp } */ +/* { dg-additional-options "-O2 -fexceptions -fopenmp -fno-delete-dead-exceptions -fno-trapping-math" } */ + +double +do_work (double do_work_pri) +{ + int i; + +#pragma omp simd + for (i = 0; i < 17; ++i) + do_work_pri = (!i ? 0.5 : i) * 2.0; + + return do_work_pri; +} + diff --git a/gcc/tree-ssa-math-opts.c b/gcc/tree-ssa-math-opts.c index c4a6492..cc8496c 100644 --- a/gcc/tree-ssa-math-opts.c +++ b/gcc/tree-ssa-math-opts.c @@ -3224,6 +3224,10 @@ convert_mult_to_fma (gimple *mul_stmt, tree op1, tree op2, fma_deferring_state *state, tree mul_cond = NULL_TREE) { tree mul_result = gimple_get_lhs (mul_stmt); + /* If there isn't a LHS then this can't be an FMA. There can be no LHS + if the statement was left just for the side-effects. */ + if (!mul_result) + return false; tree type = TREE_TYPE (mul_result); gimple *use_stmt, *neguse_stmt; use_operand_p use_p; -- 2.7.4