Teach instruction combining about the extractvalue. It can succesfully fold

useless insert-extract chains, similar to how it folds them for vectors.

Add a testcase for this.

llvm-svn: 52217

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/extractvalue.ll b/llvm/test/Transforms/InstCombine/extractvalue.ll
new file mode 100644
index 00000000000..8abeb7d315b
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/extractvalue.ll
@@ -0,0 +1,24 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep extractelement
+
+; Instcombine should fold various combinations of insertvalue and extractvalue
+; together
+declare void @bar({i32, i32} %a)
+
+define i32 @foo() {
+        ; Build a simple struct and pull values out again
+        %s1.1 = insertvalue {i32, i32} undef, i32 0, 0
+        %s1 = insertvalue {i32, i32} %s1.1, i32 1, 1
+        %v1 = extractvalue {i32, i32} %s1, 0
+        %v2 = extractvalue {i32, i32} %s1, 1
+        
+        ; Build a nested struct and pull a sub struct out of it
+        ; This requires instcombine to insert a few insertvalue instructions
+        %ns1.1 = insertvalue {i32, {i32, i32}} undef, i32 %v1, 0
+        %ns1.2 = insertvalue {i32, {i32, i32}} %ns1.1, i32 %v1, 1, 0
+        %ns1   = insertvalue {i32, {i32, i32}} %ns1.2, i32 %v2, 1, 1
+        %s2    = extractvalue {i32, {i32, i32}} %ns1, 1
+        call void @bar({i32, i32} %s2)
+        %v3 = extractvalue {i32, {i32, i32}} %ns1, 1, 1
+        ret i32 %v3
+}
+