Add same value coalescing testcase

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12865 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/2004-04-09-SameValueCoalescing.llx

@@ -0,0 +1,19 @@
+; Linear scan does not currently coalesce any two variables that have
+; overlapping live intervals. When two overlapping intervals have the same
+; value, they can be joined though.
+;
+; RUN: llvm-as < %s | llc -march=x86 -regalloc=linearscan | not grep 'mov %[A-Z]\{2,3\}, %[A-Z]\{2,3\}'
+
+int %main() {
+        %ptr = alloca uint
+        br label %Loop
+Loop:
+        %I = phi int [0, %0], [%i2, %Loop]
+        %i2 = add int %I, 1
+        %i3 = cast int %i2 to uint
+        store uint %i3, uint* %ptr
+        %C = seteq int %i2, 10
+        br bool %C, label %Out, label %Loop
+Out:
+        ret int 0
+}