https://gcc.gnu.org/g:07a2b1a40cfe3e695eef970e98cc5f682a0b79a7
commit r16-5040-g07a2b1a40cfe3e695eef970e98cc5f682a0b79a7 Author: Richard Biener <[email protected]> Date: Tue Nov 4 10:48:44 2025 +0100 Add gather_imm_use_stmts helper The following adds a helper function to gather SSA use stmts without duplicates. It steals the only padding bit in gimple to be a "infrastructure local flag" which should be used only temporarily and kept cleared. I did not add accessor functions for the flag to not encourage (ab-)uses. I have used an auto_vec<gimple *, 2> in the API to avoid heap allocations for most cases (without doing statistics). I have verified GCC 7 performs NRV optimization on the copy but I'll note while auto_vec<gimple *> has copy and assign deleted, auto_vec<gimple *, N> does not. Adding them breaks pair-fusion.cc compile. Without using 'auto' or range-for the API use is a bit awkward as that exposes the number of auto-allocated elements. The helper can be used in a range-for, see the followup for an example. * gimple.h (gimple::pad): Rename to ... (gimple::ilf): ... this. * ssa-iterators.h (gather_imm_use_stmts): Declare. * tree-ssa-operands.cc (gather_imm_use_stmts): New function. Diff: --- gcc/gimple.h | 4 ++-- gcc/ssa-iterators.h | 5 +++++ gcc/tree-ssa-operands.cc | 20 ++++++++++++++++++++ 3 files changed, 27 insertions(+), 2 deletions(-) diff --git a/gcc/gimple.h b/gcc/gimple.h index 0356bc52a5ba..9bd3f8c01970 100644 --- a/gcc/gimple.h +++ b/gcc/gimple.h @@ -250,8 +250,8 @@ struct GTY((desc ("gimple_statement_structure (&%h)"), tag ("GSS_BASE"), /* Nonzero if this statement contains volatile operands. */ unsigned has_volatile_ops : 1; - /* Padding to get subcode to 16 bit alignment. */ - unsigned pad : 1; + /* Infrastructure local flag. Always clear. */ + unsigned ilf : 1; /* The SUBCODE field can be used for tuple-specific flags for tuples that do not require subcodes. Note that SUBCODE should be at diff --git a/gcc/ssa-iterators.h b/gcc/ssa-iterators.h index 0822a98323d8..d6bd15c8ade7 100644 --- a/gcc/ssa-iterators.h +++ b/gcc/ssa-iterators.h @@ -114,6 +114,11 @@ struct auto_end_imm_use_stmt_traverse (void) ((DEST) = next_imm_use_on_stmt (&(ITER)))) +/* Use this to get a vector of all gimple stmts using SSAVAR without + duplicates. It's cheaper than FOR_EACH_IMM_USE_STMT and has no + constraints on what you are allowed to do inside an iteration + over the vector. */ +extern auto_vec<gimple *, 2> gather_imm_use_stmts (tree ssavar); extern bool single_imm_use_1 (const ssa_use_operand_t *head, use_operand_p *use_p, gimple **stmt); diff --git a/gcc/tree-ssa-operands.cc b/gcc/tree-ssa-operands.cc index a5970ac7b717..c32cb362ea1a 100644 --- a/gcc/tree-ssa-operands.cc +++ b/gcc/tree-ssa-operands.cc @@ -1416,3 +1416,23 @@ single_imm_use_1 (const ssa_use_operand_t *head, return single_use; } +/* Gather all stmts SSAVAR is used on, eliminating duplicates. */ + +auto_vec<gimple *, 2> +gather_imm_use_stmts (tree ssavar) +{ + auto_vec<gimple *, 2> stmts; + imm_use_iterator iter; + use_operand_p use_p; + FOR_EACH_IMM_USE_FAST (use_p, iter, ssavar) + { + gimple *use_stmt = USE_STMT (use_p); + if (use_stmt->ilf) + continue; + use_stmt->ilf = 1; + stmts.safe_push (use_stmt); + } + for (gimple *use_stmt : stmts) + use_stmt->ilf = 0; + return stmts; +}
