Canonicalize boolean +/- a constant to a select.

(I think it's reasonably clear that we want to have a canonical form for 
constructs like this; if anyone thinks that a select is not the best 
canonical form, please tell me.)

llvm-svn: 75531

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll b/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll
new file mode 100644
index 00000000000..105fa171c0b
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/zext-bool-add-sub.ll
@@ -0,0 +1,31 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {zext } | count 0
+
+define i32 @a(i1 %x) {
+entry:
+        %y = zext i1 %x to i32
+        %res = add i32 %y, 1
+        ret i32 %res
+}
+
+define i32 @b(i1 %x) {
+entry:
+        %y = zext i1 %x to i32
+        %res = add i32 %y, -1
+        ret i32 %res
+}
+
+define i32 @c(i1 %x) {
+entry:
+        %y = zext i1 %x to i32
+        %res = sub i32 0, %y
+        ret i32 %res
+}
+
+define i32 @d(i1 %x) {
+entry:
+        %y = zext i1 %x to i32
+        %res = sub i32 3, %y
+        ret i32 %res
+}
+
+