Tail duplication can mix incompatible registers in phi nodes
Do not tail duplicate blocks where the successor has a phi node,
and the corresponding value in that phi node uses a subregister.
http://reviews.llvm.org/D13922
llvm-svn: 250877
diff --git a/llvm/test/CodeGen/Hexagon/tail-dup-subreg-abort.ll b/llvm/test/CodeGen/Hexagon/tail-dup-subreg-abort.ll
new file mode 100644
index 0000000..82dae2c
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/tail-dup-subreg-abort.ll
@@ -0,0 +1,28 @@
+; RUN: llc -march=hexagon -O2 -disable-cgp < %s
+; REQUIRES: asserts
+;
+; Tail duplication can ignore subregister information on PHI nodes, and as
+; a result, generate COPY instructions between registers of different classes.
+; This could lead to HexagonInstrInfo::copyPhysReg aborting on an unhandled
+; src/dst combination.
+;
+define i32 @foo(i32 %x, i64 %y) nounwind {
+entry:
+ %a = icmp slt i32 %x, 0
+ %lo = trunc i64 %y to i32
+ br i1 %a, label %next, label %tail
+tail:
+ br label %join
+next:
+ %c = icmp eq i32 %x, 0
+ br i1 %c, label %b1, label %tail
+b1:
+ %t1 = lshr i64 %y, 32
+ %hi = trunc i64 %t1 to i32
+ br label %join
+join:
+ %val = phi i32 [ %hi, %b1 ], [ %lo, %tail ]
+ ret i32 %val
+}
+
+