Imported Upstream version 5.18.0.205

Former-commit-id: 7f59f7e792705db773f1caecdaa823092f4e2927

external/llvm/test/Transforms/InstCombine/consecutive-fences.ll

@@ -0,0 +1,47 @@
+; RUN: opt -instcombine -S %s | FileCheck %s
+
+; Make sure we collapse the fences in this case
+
+; CHECK-LABEL: define void @tinkywinky
+; CHECK-NEXT:   fence seq_cst
+; CHECK-NEXT:   fence syncscope("singlethread") acquire
+; CHECK-NEXT:   ret void
+; CHECK-NEXT: }
+
+define void @tinkywinky() {
+  fence seq_cst
+  fence seq_cst
+  fence seq_cst
+  fence syncscope("singlethread") acquire
+  fence syncscope("singlethread") acquire
+  fence syncscope("singlethread") acquire
+  ret void
+}
+
+; CHECK-LABEL: define void @dipsy
+; CHECK-NEXT:   fence seq_cst
+; CHECK-NEXT:   fence syncscope("singlethread") seq_cst
+; CHECK-NEXT:   ret void
+; CHECK-NEXT: }
+
+define void @dipsy() {
+  fence seq_cst
+  fence syncscope("singlethread") seq_cst
+  ret void
+}
+
+; CHECK-LABEL: define void @patatino
+; CHECK-NEXT:   fence acquire
+; CHECK-NEXT:   fence seq_cst
+; CHECK-NEXT:   fence acquire
+; CHECK-NEXT:   fence seq_cst
+; CHECK-NEXT:   ret void
+; CHECK-NEXT: }
+
+define void @patatino() {
+  fence acquire
+  fence seq_cst
+  fence acquire
+  fence seq_cst
+  ret void
+}