Add a prototype of a new peephole optimizing pass that uses LazyValue info to simplify PHIs and select's.

This pass addresses the missed optimizations from PR2581 and PR4420.

llvm-svn: 112325

3 files changed, 45 insertions, 0 deletions

diff --git a/llvm/test/Transforms/ValuePropagation/dg.exp b/llvm/test/Transforms/ValuePropagation/dg.exp
new file mode 100644
index 00000000000..de42dad163f
--- /dev/null
+++ b/llvm/test/Transforms/ValuePropagation/dg.exp
@@ -0,0 +1,3 @@
+load_lib llvm.exp
+
+RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.ll]]
diff --git a/llvm/test/Transforms/ValuePropagation/phi.ll b/llvm/test/Transforms/ValuePropagation/phi.ll
new file mode 100644
index 00000000000..f150876525c
--- /dev/null
+++ b/llvm/test/Transforms/ValuePropagation/phi.ll
@@ -0,0 +1,17 @@
+; RUN: opt < %s -value-propagation -S | FileCheck %s
+; PR2581
+
+; CHECK: @run
+define i32 @run(i1 %C) nounwind  {
+        br i1 %C, label %exit, label %body
+
+body:           ; preds = %0
+; CHECK-NOT: select
+        %A = select i1 %C, i32 10, i32 11               ; <i32> [#uses=1]
+; CHECK: ret i32 11
+        ret i32 %A
+
+exit:           ; preds = %0
+; CHECK: ret i32 10
+        ret i32 10
+}
\ No newline at end of file
diff --git a/llvm/test/Transforms/ValuePropagation/select.ll b/llvm/test/Transforms/ValuePropagation/select.ll
new file mode 100644
index 00000000000..02acc8fc76d
--- /dev/null
+++ b/llvm/test/Transforms/ValuePropagation/select.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -value-propagation -S | FileCheck %s
+; PR4420
+
+declare i1 @ext()
+; CHECK: @foo
+define i1 @foo() {
+entry:
+        %cond = tail call i1 @ext()             ; <i1> [#uses=2]
+        br i1 %cond, label %bb1, label %bb2
+
+bb1:            ; preds = %entry
+        %cond2 = tail call i1 @ext()            ; <i1> [#uses=1]
+        br i1 %cond2, label %bb3, label %bb2
+
+bb2:            ; preds = %bb1, %entry
+; CHECK-NOT: phi i1
+        %cond_merge = phi i1 [ %cond, %entry ], [ false, %bb1 ]         ; <i1> [#uses=1]
+; CHECK: ret i1 false
+        ret i1 %cond_merge
+
+bb3:            ; preds = %bb1
+        %res = tail call i1 @ext()              ; <i1> [#uses=1]
+; CHECK: ret i1 %res
+        ret i1 %res
+}
\ No newline at end of file