[llvm] [ValueTracking] Try to infer range of select from true and false values. (PR #68256)

Nikita Popov via llvm-commits llvm-commits at lists.llvm.org
Thu Oct 5 00:41:34 PDT 2023


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@@ -0,0 +1,15 @@
+; RUN: opt < %s -aa-pipeline=basic-aa -passes=aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
+
+ at a = dso_local local_unnamed_addr global [10 x i32] zeroinitializer, align 4
+
+; CHECK-LABEL: Function: select_in_gep
+; CHECK: NoAlias: i32* %arrayidx, i32* getelementptr inbounds ([10 x i32], ptr @a, i64 0, i64 3)
+define i32 @select_in_gep(i1 %c)  {
+entry:
+  %cond = select i1 %c, i64 2, i64 1
+  %0 = load i32, ptr getelementptr inbounds ([10 x i32], ptr @a, i64 0, i64 3), align 4
----------------
nikic wrote:

This load is unnecessary, you can store a constant to `%arrayidx`.

https://github.com/llvm/llvm-project/pull/68256


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