From 1d5c7584fd6e72bfdbede86cef5ff04ae35f9744 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 3 Feb 2022 11:20:59 +0100 Subject: [PATCH] debug/104337 - avoid messing with the abstract origin chain in NRV The following avoids NRV from massaging DECL_ABSTRACT_ORIGIN after variable creation since NRV runs _after_ the function was inlined and thus affects the inlined variables copy indirectly. We may adjust the abstract origin of a variable only at the point we create it, not further along the path since otherwise the (new) invariant that the abstract origin is always the ultimate origin cannot be maintained. The intent of what NRV does is OK I guess and it may improve the debug experience. But I also notice we do SET_DECL_VALUE_EXPR (found, result); DECL_HAS_VALUE_EXPR_P (found) = 1; the code is there since the merge from tree-ssa which added tree-nrv.c. Jakub added the DECL_VALUE_EXPR in g:938650d8fddb878f623e315f0b7fd94b217efa96 and Jason added the abstract origin setting conditional in g:7716876bbd3a The follwoing takes the radical approach and remove the attempt to "optimize" the debug info. The gdb testsuites show no regressions. 2022-02-03 Richard Biener PR debug/104337 * tree-nrv.cc (pass_nrv::execute): Remove tieing result and found together via DECL_ABSTRACT_ORIGIN. * gcc.dg/debug/pr104337.c: New testcase. --- gcc/testsuite/gcc.dg/debug/pr104337.c | 15 +++++++++++++++ gcc/tree-nrv.cc | 13 ------------- 2 files changed, 15 insertions(+), 13 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/debug/pr104337.c diff --git a/gcc/testsuite/gcc.dg/debug/pr104337.c b/gcc/testsuite/gcc.dg/debug/pr104337.c new file mode 100644 index 00000000000..d15680fbf1a --- /dev/null +++ b/gcc/testsuite/gcc.dg/debug/pr104337.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ + +struct a { + unsigned b : 7; +}; +inline __attribute__((optimize(3))) __attribute__((always_inline)) struct a +c() { + struct a d; + return d; +} +void e() { + for (;;) + c(); +} +int main() {} diff --git a/gcc/tree-nrv.cc b/gcc/tree-nrv.cc index a67736dae5c..b96d5b86f27 100644 --- a/gcc/tree-nrv.cc +++ b/gcc/tree-nrv.cc @@ -236,19 +236,6 @@ pass_nrv::execute (function *fun) fprintf (dump_file, "\n"); } - /* At this point we know that all the return statements return the - same local which has suitable attributes for NRV. Copy debugging - information from FOUND to RESULT if it will be useful. But don't set - DECL_ABSTRACT_ORIGIN to point at another function. */ - if (!DECL_IGNORED_P (found) - && !(DECL_ABSTRACT_ORIGIN (found) - && DECL_CONTEXT (DECL_ABSTRACT_ORIGIN (found)) != current_function_decl)) - { - DECL_NAME (result) = DECL_NAME (found); - DECL_SOURCE_LOCATION (result) = DECL_SOURCE_LOCATION (found); - DECL_ABSTRACT_ORIGIN (result) = DECL_ABSTRACT_ORIGIN (found); - } - TREE_ADDRESSABLE (result) |= TREE_ADDRESSABLE (found); /* Now walk through the function changing all references to VAR to be