Subzero: Fix some legalization issues involving immediates.

tests_lit/llvm2ice_tests/switch-opt.ll

 ; This tests a switch statement, including multiple branches to the
 ; same label which also results in phi instructions with multiple
 ; entries for the same incoming edge.
 
 ; RUN: %llvm2ice --verbose inst %s | FileCheck %s
 ; RUN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
 ; RUN: %llvm2iceinsts %s | %szdiff %s | FileCheck --check-prefix=DUMP %s
 ; RUN: %llvm2iceinsts --pnacl %s | %szdiff %s \
 ; RUN:                           | FileCheck --check-prefix=DUMP %s
 
@@ skipping 19 matching lines @@
 
 sw.bb2:                                           ; preds = %sw.bb1, %entry, %entry
   %result.0 = phi i32 [ 1, %entry ], [ 1, %entry ], [ %phitmp, %sw.bb1 ]
   br label %sw.epilog
 
 sw.epilog:                                        ; preds = %sw.bb2, %sw.default, %entry, %entry, %entry
   %result.1 = phi i32 [ %add, %sw.default ], [ %result.0, %sw.bb2 ], [ 17, %entry ], [ 17, %entry ], [ 17, %entry ]
   ret i32 %result.1
 }
 
+; Check for a valid addressing mode when the switch operand is an
+; immediate.  It's important that there is exactly one case, because
+; for two or more cases the source operand is legalized into a
+; register.
+define i32 @testSwitchImm() {
+entry:
+  switch i32 10, label %sw.default [
+    i32 1, label %sw.default
+  ]
+
+sw.default:
+  ret i32 20
+}
+; CHECK-LABEL: testSwitchImm
+; CHECK-NOT: cmp {{[0-9]*}},
+
 ; CHECK-NOT: ICE translation error
 ; ERRORS-NOT: ICE translation error
 ; DUMP-NOT: SZ