[LAA] rewrite a test to make it more robust (#93197)

The test select-dependence.ll can be eliminated completely by dce, as it
returns a constant, and doesn't write any arguments. Lift out the local
allocas into arguments, so that it is less nonsensical. While at it,
rename the variables for greater readability, and regenerate the test
with UpdateTestChecks.

Author: artagnon

llvm/test/Analysis/LoopAccessAnalysis/select-dependence.ll

@@ -1,30 +1,41 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 5
 ; RUN: opt -passes='print<access-info>' -disable-output 2>&1 < %s | FileCheck %s
 
-; CHECK: Dependences:
-; CHECK-NEXT: Unknown:
-; CHECK-NEXT: %t63 = load double, ptr %t62, align 8 ->
-; CHECK-NEXT: store double %t63, ptr %t64, align 8
-
-define i32 @test() {
-   %a1 = alloca [128 x double], align 8
-   %a2 = alloca [128 x double], align 8
-   %a3 = alloca [128 x double], align 8
-   %t30 = getelementptr double, ptr %a2, i64 -32
+define void @test(ptr noalias %x, ptr noalias %y, ptr noalias %z) {
+; CHECK-LABEL: 'test'
+; CHECK-NEXT:    loop:
+; CHECK-NEXT:      Report: unsafe dependent memory operations in loop. Use #pragma clang loop distribute(enable) to allow loop distribution to attempt to isolate the offending operations into a separate loop
+; CHECK-NEXT:  Unknown data dependence.
+; CHECK-NEXT:      Dependences:
+; CHECK-NEXT:        Unknown:
+; CHECK-NEXT:            %load = load double, ptr %gep.sel, align 8 ->
+; CHECK-NEXT:            store double %load, ptr %gep.sel2, align 8
+; CHECK-EMPTY:
+; CHECK-NEXT:      Run-time memory checks:
+; CHECK-NEXT:      Grouped accesses:
+; CHECK-EMPTY:
+; CHECK-NEXT:      Non vectorizable stores to invariant address were not found in loop.
+; CHECK-NEXT:      SCEV assumptions:
+; CHECK-EMPTY:
+; CHECK-NEXT:      Expressions re-written:
+;
+entry:
+   %gep.y = getelementptr double, ptr %y, i64 -32
    br label %loop
 
 loop:
-   %t58 = phi i64 [ %t65, %loop ], [ 0, %0 ]
-   %t59 = icmp ule i64 %t58, 32
-   %t60 = select i1 %t59, ptr %a1, ptr %t30
-   %t62 = getelementptr inbounds double, ptr %t60, i64 %t58
-   %t63 = load double, ptr %t62, align 8
-   %t61 = select i1 %t59, ptr %a2, ptr %a3
-   %t64 = getelementptr inbounds double, ptr %t61, i64 %t58
-   store double %t63, ptr %t64, align 8
-   %t65 = add nuw nsw i64 %t58, 1
-   %t66 = icmp eq i64 %t65, 94
-   br i1 %t66, label %exit, label %loop
+   %iv = phi i64 [ %iv.next, %loop ], [ 0, %entry ]
+   %icmp = icmp ule i64 %iv, 32
+   %sel = select i1 %icmp, ptr %x, ptr %gep.y
+   %gep.sel = getelementptr inbounds double, ptr %sel, i64 %iv
+   %load = load double, ptr %gep.sel, align 8
+   %sel2 = select i1 %icmp, ptr %y, ptr %z
+   %gep.sel2 = getelementptr inbounds double, ptr %sel2, i64 %iv
+   store double %load, ptr %gep.sel2, align 8
+   %iv.next = add nuw nsw i64 %iv, 1
+   %exit.cond = icmp eq i64 %iv, 94
+   br i1 %exit.cond, label %exit, label %loop
 
 exit:
-   ret i32 0
+   ret void
 }