Subzero: Fold icmp into br/select lowering.

tests_lit/llvm2ice_tests/8bit.pnacl.ll

Index: tests_lit/llvm2ice_tests/8bit.pnacl.ll
diff --git a/tests_lit/llvm2ice_tests/8bit.pnacl.ll b/tests_lit/llvm2ice_tests/8bit.pnacl.ll
index 4f48cf46923cdf946787ce1185144683c98c0b6f..4987a1d5cfdc1269958abc7eb8630a2ea0ef9335 100644
--- a/tests_lit/llvm2ice_tests/8bit.pnacl.ll
+++ b/tests_lit/llvm2ice_tests/8bit.pnacl.ll
@@ -3,6 +3,8 @@
 ; RUN: %p2i --filetype=obj --disassemble -i %s --args -O2 | FileCheck %s
 ; RUN: %p2i --filetype=obj --disassemble -i %s --args -Om1 | FileCheck %s
 
+declare void @useInt(i32 %x)
+
 define internal i32 @add8Bit(i32 %a, i32 %b) {
 entry:
   %a_8 = trunc i32 %a to i8
@@ -278,6 +280,9 @@ entry:
   %cmp = icmp slt i8 %a_8, %b_8
   %ret = select i1 %cmp, i8 %a_8, i8 %b_8
   %ret_ext = zext i8 %ret to i32
+  ; Create a "fake" use of %cmp to prevent O2 bool folding.
+  %d1 = zext i1 %cmp to i32
+  call void @useInt(i32 %d1)
   ret i32 %ret_ext
 }
 ; CHECK-LABEL: selectI8Var