[IR] Use User::getHungOffOperands() in HungoffOperandTraits::op_begin/op_end(). NFC

[topperc]

User::getOperandList has to check the HasHungOffUses bit in Value to determine how the operand list is stored. If we're using HungoffOperandTraits we can assume how it is stored without checking the flag.

Noticed that the for loop in matchSimpleRecurrence was triggering loop unswitch when built with clang due to specializing based on how the operand list of the PHINode was stored.

This reduces the size of llc on my local Release+Asserts build by around 41K.

[llvmbot]

@llvm/pr-subscribers-llvm-ir

Author: Craig Topper (topperc)

Changes

User::getOperandList has to check the HasHungOffUses bit in Value to determine how the opernad list is stored. If we're using HungoffOperandTraits we can assume how it is stored without checking the flag.

Noticed that the for loop in matchSimpleRecurrence was triggering loop unswitch when built with clang due to specializing based on how the operand list of the PHINode was stored.

This reduces the size of llc on my local Release+Asserts build by around 41K.

---

Full diff: https://github.com/llvm/llvm-project/pull/74744.diff

1 Files Affected:

• (modified) llvm/include/llvm/IR/OperandTraits.h (+2-2)

diff --git a/llvm/include/llvm/IR/OperandTraits.h b/llvm/include/llvm/IR/OperandTraits.h
index 979ad35019f8c..ffece6324aab0 100644
--- a/llvm/include/llvm/IR/OperandTraits.h
+++ b/llvm/include/llvm/IR/OperandTraits.h
@@ -94,10 +94,10 @@ struct VariadicOperandTraits {
 template <unsigned MINARITY = 1>
 struct HungoffOperandTraits {
   static Use *op_begin(User* U) {
-    return U->getOperandList();
+    return U->getHungOffOperands();
   }
   static Use *op_end(User* U) {
-    return U->getOperandList() + U->getNumOperands();
+    return U->getHungOffOperands() + U->getNumOperands();
   }
   static unsigned operands(const User *U) {
     return U->getNumOperands();

[github-actions]

⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:

git-clang-format --diff 04cbfcc33ae9a1bc440d553abc73b02421cf6ad2 0eac008df5bb72428277d16dc06663846ad491bf -- llvm/include/llvm/IR/OperandTraits.h

View the diff from clang-format here.

diff --git a/llvm/include/llvm/IR/OperandTraits.h b/llvm/include/llvm/IR/OperandTraits.h
index ffece6324a..50e96061b6 100644
--- a/llvm/include/llvm/IR/OperandTraits.h
+++ b/llvm/include/llvm/IR/OperandTraits.h
@@ -93,9 +93,7 @@ struct VariadicOperandTraits {
 
 template <unsigned MINARITY = 1>
 struct HungoffOperandTraits {
-  static Use *op_begin(User* U) {
-    return U->getHungOffOperands();
-  }
+  static Use *op_begin(User *U) { return U->getHungOffOperands(); }
   static Use *op_end(User* U) {
     return U->getHungOffOperands() + U->getNumOperands();
   }

[preames]

LGTM - Good find!