Switch to select optimization for two-case switches
This is the same optimization of r219233 with modifications to support PHIs with multiple incoming edges from the same block
and a test to check that this condition is handled.
llvm-svn: 219656
diff --git a/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll b/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll
new file mode 100644
index 0000000..ddf5d1f
--- /dev/null
+++ b/llvm/test/Transforms/SimplifyCFG/switch-to-select-multiple-edge-per-block-phi.ll
@@ -0,0 +1,40 @@
+; RUN: opt < %s -simplifycfg -S | FileCheck %s
+
+; a, b;
+; fn1() {
+; if (b)
+; if (a == 0 || a == 5)
+; return a;
+; return 0;
+; }
+
+; Checking that we handle correctly the case when we have a switch
+; branching multiple times to the same block
+
+@b = common global i32 0, align 4
+@a = common global i32 0, align 4
+
+; Function Attrs: nounwind
+define i32 @fn1() {
+; CHECK-LABEL: @fn1
+; CHECK: %switch.selectcmp1 = icmp eq i32 %1, 5
+; CHECK: %switch.select2 = select i1 %switch.selectcmp1, i32 5, i32 %switch.select
+entry:
+ %0 = load i32* @b, align 4
+ %tobool = icmp eq i32 %0, 0
+ br i1 %tobool, label %if.end3, label %if.then
+
+if.then:
+ %1 = load i32* @a, align 4
+ switch i32 %1, label %if.end3 [
+ i32 5, label %return
+ i32 0, label %return
+ ]
+
+if.end3:
+ br label %return
+
+return:
+ %retval.0 = phi i32 [ 0, %if.end3 ], [ %1, %if.then ], [ %1, %if.then ]
+ ret i32 %retval.0
+}