[llvm] [CodeGen] Avoid repeated hash lookups (NFC) (PR #125463)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-regalloc

Author: Kazu Hirata (kazutakahirata)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/125463.diff


1 Files Affected:

- (modified) llvm/include/llvm/CodeGen/LiveIntervals.h (+6-4) 


``````````diff
diff --git a/llvm/include/llvm/CodeGen/LiveIntervals.h b/llvm/include/llvm/CodeGen/LiveIntervals.h
index 540651ea114427..708917be497ef6 100644
--- a/llvm/include/llvm/CodeGen/LiveIntervals.h
+++ b/llvm/include/llvm/CodeGen/LiveIntervals.h
@@ -149,8 +149,9 @@ class LiveIntervals {
   LiveInterval &createEmptyInterval(Register Reg) {
     assert(!hasInterval(Reg) && "Interval already exists!");
     VirtRegIntervals.grow(Reg.id());
-    VirtRegIntervals[Reg.id()] = createInterval(Reg);
-    return *VirtRegIntervals[Reg.id()];
+    auto &Interval = VirtRegIntervals[Reg.id()];
+    Interval = createInterval(Reg);
+    return *Interval;
   }
 
   LiveInterval &createAndComputeVirtRegInterval(Register Reg) {
@@ -168,8 +169,9 @@ class LiveIntervals {
 
   /// Interval removal.
   void removeInterval(Register Reg) {
-    delete VirtRegIntervals[Reg];
-    VirtRegIntervals[Reg] = nullptr;
+    auto &Interval = VirtRegIntervals[Reg];
+    delete Interval;
+    Interval = nullptr;
   }
 
   /// Given a register and an instruction, adds a live segment from that

``````````

</details>


https://github.com/llvm/llvm-project/pull/125463