Imported Upstream version 5.18.0.205

Former-commit-id: 7f59f7e792705db773f1caecdaa823092f4e2927

external/llvm/test/Transforms/PhaseOrdering/globalaa-retained.ll

@@ -0,0 +1,66 @@
+; RUN: opt -O3 -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64"
+
+@v = internal unnamed_addr global i32 0, align 4
+@p = common global i32* null, align 8
+
+
+; This test checks that a number of loads and stores are eliminated,
+; that can only be eliminated based on GlobalsAA information. As such,
+; it tests that GlobalsAA information is retained until the passes
+; that perform this optimization, and it protects against accidentally
+; dropping the GlobalsAA information earlier in the pipeline, which
+; has happened a few times.
+
+; GlobalsAA invalidation might happen later in the FunctionPassManager
+; pipeline than the optimization eliminating unnecessary loads/stores.
+; Since GlobalsAA is a module-level analysis, any FunctionPass
+; invalidating the GlobalsAA information will affect FunctionPass
+; pipelines that execute later. For example, assume a FunctionPass1 |
+; FunctionPass2 pipeline and 2 functions to be processed: f1 and f2.
+; Assume furthermore that FunctionPass1 uses GlobalsAA info to do an
+; optimization, and FunctionPass2 invalidates GlobalsAA. Assume the
+; function passes run in the following order: FunctionPass1(f1),
+; FunctionPass2(f1), FunctionPass1(f2), FunctionPass2(f2). Then
+; FunctionPass1 will not be able to optimize f2, since GlobalsAA will
+; have been invalidated in FuntionPass2(f1).
+
+; To try and also test this scenario, there is an empty function
+; before and after the function we're checking so that one of them
+; will be processed by the whole set of FunctionPasses before @f. That
+; will ensure that if the invalidation happens, it happens before the
+; actual optimizations on @f start.
+define void @bar() {
+entry:
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @f(i32 %n) {
+entry:
+  %0 = load i32, i32* @v, align 4
+  %inc = add nsw i32 %0, 1
+  store i32 %inc, i32* @v, align 4
+  %1 = load i32*, i32** @p, align 8
+  store i32 %n, i32* %1, align 4
+  %2 = load i32, i32* @v, align 4
+  %inc1 = add nsw i32 %2, 1
+  store i32 %inc1, i32* @v, align 4
+  ret void
+}
+
+; check variable v is loaded/stored only once after optimization,
+; which should be prove that globalsAA survives until the optimization
+; that can use it to optimize away the duplicate load/stores on
+; variable v.
+; CHECK:     load i32, i32* @v, align 4
+; CHECK:     store i32 {{.*}}, i32* @v, align 4
+; CHECK-NOT: load i32, i32* @v, align 4
+; CHECK-NOT:     store i32 {{.*}}, i32* @v, align 4
+
+; Same as @bar above, in case the functions are processed in reverse order.
+define void @bar2() {
+entry:
+  ret void
+}