[mips] Enforce compact branch restrictions

Check both operands for use of the $zero register which cannot be used with
a compact branch instruction.

Reviewers: dsanders, vkalintris

Differential Review: https://reviews.llvm.org/D23547

llvm-svn: 278824

1 files changed, 28 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Mips/compactbranches/no-beqzc-bnezc.ll b/llvm/test/CodeGen/Mips/compactbranches/no-beqzc-bnezc.ll
index 969e3cbfb0f..7a9f287c1b4 100644
--- a/llvm/test/CodeGen/Mips/compactbranches/no-beqzc-bnezc.ll
+++ b/llvm/test/CodeGen/Mips/compactbranches/no-beqzc-bnezc.ll
@@ -100,3 +100,31 @@ define i64 @f5(i64 %a, i64 %b) {
   if.end:
     ret i64 0
 }
+
+define i32 @f6(i32 %a) {
+; CHECK-LABEL: f6:
+; CHECK: beqzc ${{[0-9]+}}, $BB
+
+  %cmp = icmp eq i32 %a, 0
+  br i1 %cmp, label %if.then, label %if.end
+
+  if.then:
+    ret i32 1
+
+  if.end:
+    ret i32 0
+}
+
+define i32 @f7(i32 %a) {
+; CHECK-LABEL: f7:
+; CHECK: bnezc ${{[0-9]+}}, $BB
+
+  %cmp = icmp eq i32 0, %a
+  br i1 %cmp, label %if.then, label %if.end
+
+  if.then:
+    ret i32 1
+
+  if.end:
+    ret i32 0
+}