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author | Jason Merrill <jason@redhat.com> | 2022-09-19 19:08:10 +0200 |
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committer | Jason Merrill <jason@redhat.com> | 2022-09-29 13:48:20 -0400 |
commit | 32b2eb59fb904926eff77811e08766a8ae6804a7 (patch) | |
tree | b5d170cf847014cde68feb6c197515e3d9fdec99 /gcc/cp | |
parent | af9034827e8f06f10767064e9fc7443b94e08184 (diff) | |
download | gcc-32b2eb59fb904926eff77811e08766a8ae6804a7.zip gcc-32b2eb59fb904926eff77811e08766a8ae6804a7.tar.gz gcc-32b2eb59fb904926eff77811e08766a8ae6804a7.tar.bz2 |
c++: reduce temporaries in ?:
When the sides of ?: are class prvalues, we wrap the COND_EXPR in a
TARGET_EXPR so that both sides will initialize the same temporary. But in
this case we were stripping the outer TARGET_EXPR and conditionally creating
different temporaries, unnecessarily using extra stack. The
recently added TARGET_EXPR_NO_ELIDE flag avoids this.
gcc/cp/ChangeLog:
* call.cc (build_conditional_expr): Set TARGET_EXPR_NO_ELIDE on the
outer TARGET_EXPR.
gcc/testsuite/ChangeLog:
* g++.dg/tree-ssa/cond-temp1.C: New test.
Diffstat (limited to 'gcc/cp')
-rw-r--r-- | gcc/cp/call.cc | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 3506b0f..9fad3cb 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -6009,7 +6009,13 @@ build_conditional_expr (const op_location_t &loc, but now we sometimes wrap them in NOP_EXPRs so the test would fail. */ if (CLASS_TYPE_P (TREE_TYPE (result))) - result = get_target_expr (result, complain); + { + result = get_target_expr (result, complain); + /* Tell gimplify_modify_expr_rhs not to strip this in + assignment context: we want both arms to initialize + the same temporary. */ + TARGET_EXPR_NO_ELIDE (result) = true; + } /* If this expression is an rvalue, but might be mistaken for an lvalue, we must add a NON_LVALUE_EXPR. */ result = rvalue (result); |