[llvm] 635288d - [llvm-diff] Check for recursive initialiers

[Bill Wendling via llvm-commits]

Author: Bill Wendling
Date: 2021-07-21T14:21:21-07:00
New Revision: 635288d215b1147e624cf37f9c5f66ae35c15b74

URL: https://github.com/llvm/llvm-project/commit/635288d215b1147e624cf37f9c5f66ae35c15b74
DIFF: https://github.com/llvm/llvm-project/commit/635288d215b1147e624cf37f9c5f66ae35c15b74.diff

LOG: [llvm-diff] Check for recursive initialiers

We need to check for recursive initializers in the "ConstantStruct"
case.

Differential Revision: https://reviews.llvm.org/D105616

Added: 
    

Modified: 
    llvm/test/tools/llvm-diff/initializers.ll
    llvm/tools/llvm-diff/DifferenceEngine.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-
diff /initializers.ll b/llvm/test/tools/llvm-
diff /initializers.ll
index 93cabfba54f2..d4b0d8f8a231 100644
--- a/llvm/test/tools/llvm-
diff /initializers.ll
+++ b/llvm/test/tools/llvm-
diff /initializers.ll
@@ -36,3 +36,12 @@ define internal i32 @qux() {
   call void undef(%struct.mutex* @vmx_l1d_flush_mutex)
   ret i32 undef
 }
+
+; An initializer could use itself as part of the initialization.
+
+ at kvm_debugfs_entries = internal global %struct.list_head { %struct.list_head* @kvm_debugfs_entries, %struct.list_head* @kvm_debugfs_entries }, align 8
+
+define i64 @mux() {
+  %1 = load i8*, i8** bitcast (%struct.list_head* @kvm_debugfs_entries to i8**), align 8
+  ret i64 undef
+}

diff  --git a/llvm/tools/llvm-
diff /DifferenceEngine.cpp b/llvm/tools/llvm-
diff /DifferenceEngine.cpp
index b3a6ba83c1e4..eb746cd2a865 100644
--- a/llvm/tools/llvm-
diff /DifferenceEngine.cpp
+++ b/llvm/tools/llvm-
diff /DifferenceEngine.cpp
@@ -490,6 +490,16 @@ class FunctionDifferenceEngine {
         const Value *LAgg = CSL->getAggregateElement(I);
         const Value *RAgg = CSR->getAggregateElement(I);
 
+        if (LAgg == SavedLHS || RAgg == SavedRHS) {
+          if (LAgg != SavedLHS || RAgg != SavedRHS)
+            // If the left and right operands aren't both re-analyzing the
+            // variable, then the initialiers don't match, so report "false".
+            // Otherwise, we skip these operands..
+            return false;
+
+          continue;
+        }
+
         if (!equivalentAsOperands(LAgg, RAgg)) {
           return false;
         }