[llvm] EarlyCSE: fix CmpPredicate duplicate-hashing (PR #119902)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon updated https://github.com/llvm/llvm-project/pull/119902

>From 8a9fa55e5c5bac8b4bc0e243b27642f8e71392fd Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Fri, 13 Dec 2024 17:10:42 +0000
Subject: [PATCH 1/2] EarlyCSE: fix CmpPredicate duplicate-hashing

Fixes #119893.
---
 llvm/include/llvm/IR/CmpPredicate.h     | 6 ------
 llvm/lib/IR/Instructions.cpp            | 4 ----
 llvm/lib/Transforms/Scalar/EarlyCSE.cpp | 3 ++-
 3 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/llvm/include/llvm/IR/CmpPredicate.h b/llvm/include/llvm/IR/CmpPredicate.h
index ce78e4311f9f82..9aa1449465f5ff 100644
--- a/llvm/include/llvm/IR/CmpPredicate.h
+++ b/llvm/include/llvm/IR/CmpPredicate.h
@@ -71,13 +71,7 @@ class CmpPredicate {
 
   /// Get the swapped predicate of a CmpInst.
   static CmpPredicate getSwapped(const CmpInst *Cmp);
-
-  /// Provided to facilitate storing a CmpPredicate in data structures that
-  /// require hashing.
-  friend hash_code hash_value(const CmpPredicate &Arg); // NOLINT
 };
-
-[[nodiscard]] hash_code hash_value(const CmpPredicate &Arg);
 } // namespace llvm
 
 #endif
diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
index d1da02c744f18c..2d6fe40f4c1de0 100644
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -3946,10 +3946,6 @@ CmpPredicate CmpPredicate::getSwapped(const CmpInst *Cmp) {
   return getSwapped(get(Cmp));
 }
 
-hash_code llvm::hash_value(const CmpPredicate &Arg) { // NOLINT
-  return hash_combine(Arg.Pred, Arg.HasSameSign);
-}
-
 //===----------------------------------------------------------------------===//
 //                        SwitchInst Implementation
 //===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
index 682c5c3d8c6340..3a0ae6b01a1144 100644
--- a/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ b/llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -290,7 +290,8 @@ static unsigned getHashValueImpl(SimpleValue Val) {
       Pred = CmpInst::getInversePredicate(Pred);
       std::swap(A, B);
     }
-    return hash_combine(Inst->getOpcode(), Pred, X, Y, A, B);
+    return hash_combine(Inst->getOpcode(),
+                        static_cast<CmpInst::Predicate>(Pred), X, Y, A, B);
   }
 
   if (CastInst *CI = dyn_cast<CastInst>(Inst))

>From 8c866c9c36fa72c7daa40696d9a73563e2640680 Mon Sep 17 00:00:00 2001
From: Ramkumar Ramachandra <ramkumar.ramachandra at codasip.com>
Date: Fri, 13 Dec 2024 18:02:18 +0000
Subject: [PATCH 2/2] test/EarlyCSE: add reduced test

---
 llvm/test/Transforms/EarlyCSE/pr119893.ll | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 llvm/test/Transforms/EarlyCSE/pr119893.ll

diff --git a/llvm/test/Transforms/EarlyCSE/pr119893.ll b/llvm/test/Transforms/EarlyCSE/pr119893.ll
new file mode 100644
index 00000000000000..c9ea315c9fea47
--- /dev/null
+++ b/llvm/test/Transforms/EarlyCSE/pr119893.ll
@@ -0,0 +1,21 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -passes=early-cse -S %s | FileCheck %s
+
+define i32 @samesign_hash_bug(i16 %v) {
+; CHECK-LABEL: define i32 @samesign_hash_bug(
+; CHECK-SAME: i16 [[V:%.*]]) {
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i16 [[V]] to i32
+; CHECK-NEXT:    [[ICMP_SAMESIGN:%.*]] = icmp ugt i32 [[ZEXT]], 31
+; CHECK-NEXT:    [[SELECT_ICMP_SAMESIGN:%.*]] = select i1 [[ICMP_SAMESIGN]], i32 0, i32 1
+; CHECK-NEXT:    [[SELECT_ICMP:%.*]] = select i1 [[ICMP_SAMESIGN]], i32 1, i32 0
+; CHECK-NEXT:    ret i32 [[SELECT_ICMP]]
+;
+  %zext = zext i16 %v to i32
+  %icmp.samesign = icmp samesign ugt i32 %zext, 31
+  %select.icmp.samesign = select i1 %icmp.samesign, i32 0, i32 1
+  %ashr = ashr i32 0, %select.icmp.samesign
+  %icmp = icmp ugt i32 %zext, 31
+  %select.icmp = select i1 %icmp, i32 1, i32 0
+  %ret = add i32 %ashr, %select.icmp
+  ret i32 %ret
+}