Teach BasicAA how to analyze Select instructions, and make it more

aggressive on PHI instructions. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85158 91177308-0d34-0410-b5e6-96231b3b80d8
2026-04-26 12:20:42 +00:00 · 2009-10-26 21:55:43 +00:00
parent cadd4b9ced
commit 6665b0ea68
2 changed files with 149 additions and 2 deletions
@@ -0,0 +1,73 @@
+; RUN: opt < %s -aa-eval -print-all-alias-modref-info -disable-output \
+; RUN:   |& grep {NoAlias:	double\\* \[%\]a, double\\* \[%\]b\$} | count 4
+
+; BasicAA should detect NoAliases in PHIs and Selects.
+
+; Two PHIs in the same block.
+define void @foo(i1 %m, double* noalias %x, double* noalias %y) {
+entry:
+  br i1 %m, label %true, label %false
+
+true:
+  br label %exit
+
+false:
+  br label %exit
+
+exit:
+  %a = phi double* [ %x, %true ], [ %y, %false ]
+  %b = phi double* [ %x, %false ], [ %y, %true ]
+  volatile store double 0.0, double* %a
+  volatile store double 1.0, double* %b
+  ret void
+}
+
+; Two selects with the same condition.
+define void @bar(i1 %m, double* noalias %x, double* noalias %y) {
+entry:
+  %a = select i1 %m, double* %x, double* %y
+  %b = select i1 %m, double* %y, double* %x
+  volatile store double 0.000000e+00, double* %a
+  volatile store double 1.000000e+00, double* %b
+  ret void
+}
+
+; Two PHIs with disjoint sets of inputs.
+define void @qux(i1 %m, double* noalias %x, double* noalias %y,
+                 i1 %n, double* noalias %v, double* noalias %w) {
+entry:
+  br i1 %m, label %true, label %false
+
+true:
+  br label %exit
+
+false:
+  br label %exit
+
+exit:
+  %a = phi double* [ %x, %true ], [ %y, %false ]
+  br i1 %n, label %ntrue, label %nfalse
+
+ntrue:
+  br label %nexit
+
+nfalse:
+  br label %nexit
+
+nexit:
+  %b = phi double* [ %v, %ntrue ], [ %w, %nfalse ]
+  volatile store double 0.0, double* %a
+  volatile store double 1.0, double* %b
+  ret void
+}
+
+; Two selects with disjoint sets of arms.
+define void @fin(i1 %m, double* noalias %x, double* noalias %y,
+                 i1 %n, double* noalias %v, double* noalias %w) {
+entry:
+  %a = select i1 %m, double* %x, double* %y
+  %b = select i1 %n, double* %v, double* %w
+  volatile store double 0.000000e+00, double* %a
+  volatile store double 1.000000e+00, double* %b
+  ret void
+}