[GlobalOpt] Localize some globals that have non-instruction users

We currently bail out of global localization if the global has non-instruction users. However, often these can be simple bitcasts or constant-GEPs, which we can easily turn into instructions before localizing. Be a bit more aggressive.

llvm-svn: 253584

1 files changed, 28 insertions, 0 deletions

diff --git a/llvm/test/Transforms/GlobalOpt/localize-constexpr.ll b/llvm/test/Transforms/GlobalOpt/localize-constexpr.ll
new file mode 100644
index 00000000000..6754533a50c
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/localize-constexpr.ll
@@ -0,0 +1,28 @@
+; RUN: opt -S < %s -globalopt | FileCheck %s
+
+@G = internal global i32 42
+
+define i8 @f() norecurse {
+; CHECK-LABEL: @f
+; CHECK: alloca
+; CHECK-NOT: @G
+; CHECK: }
+  store i32 42, i32* @G
+  %a = load i8, i8* bitcast (i32* @G to i8*)
+  ret i8 %a
+}
+
+@H = internal global i32 42
+@Halias = internal alias i32, i32* @H
+
+; @H can't be localized because @Halias uses it, and @Halias can't be converted to an instruction.
+define i8 @g() norecurse {
+; CHECK-LABEL: @g
+; CHECK-NOT: alloca
+; CHECK: @H
+; CHECK: }
+  store i32 42, i32* @H
+  %a = load i8, i8* bitcast (i32* @H to i8*)
+  ret i8 %a
+}
+