commit 025ea891faaffa832116e5411bfcdb70d256b494
author Jeremy Gebben <jeremyg@lunarg.com> Mon Dec 19 11:08:01 2022 -0700
committer GitHub <noreply@github.com> Mon Dec 19 13:08:01 2022 -0500
tree 390da45083cb35a2153504db48a7d694428b1c16
parent 1c287b03d3dc51c28b9c679e146c269969ce8972

Optimize allocation of spvtools::opt::Instruction::operands_ (#5024)

Reserve space for the entire operand list rather than adding them
one a time.

source/opt/instruction.cpp

diff --git a/source/opt/instruction.cpp b/source/opt/instruction.cpp
index ab3ca0f..ece6baf 100644
--- a/source/opt/instruction.cpp
+++ b/source/opt/instruction.cpp
@@ -73,6 +73,7 @@
       unique_id_(c->TakeNextUniqueId()),
       dbg_line_insts_(std::move(dbg_line)),
       dbg_scope_(kNoDebugScope, kNoInlinedAt) {
+  operands_.reserve(inst.num_operands);
   for (uint32_t i = 0; i < inst.num_operands; ++i) {
     const auto& current_payload = inst.operands[i];
     operands_.emplace_back(
@@ -92,6 +93,7 @@
       has_result_id_(inst.result_id != 0),
       unique_id_(c->TakeNextUniqueId()),
       dbg_scope_(dbg_scope) {
+  operands_.reserve(inst.num_operands);
   for (uint32_t i = 0; i < inst.num_operands; ++i) {
     const auto& current_payload = inst.operands[i];
     operands_.emplace_back(
@@ -110,6 +112,14 @@
       unique_id_(c->TakeNextUniqueId()),
       operands_(),
       dbg_scope_(kNoDebugScope, kNoInlinedAt) {
+  size_t operands_size = in_operands.size();
+  if (has_type_id_) {
+    operands_size++;
+  }
+  if (has_result_id_) {
+    operands_size++;
+  }
+  operands_.reserve(operands_size);
   if (has_type_id_) {
     operands_.emplace_back(spv_operand_type_t::SPV_OPERAND_TYPE_TYPE_ID,
                            std::initializer_list<uint32_t>{ty_id});