Fix bug when atomic load is fused with an arith op (and not in the entry BB)

tests_lit/llvm2ice_tests/nacl-atomic-intrinsics.ll

 ; This tests each of the supported NaCl atomic instructions for every
 ; size allowed.
 
 ; RUN: %llvm2ice -O2 --verbose none %s | FileCheck %s
 ; RUN: %llvm2ice -O2 --verbose none %s | FileCheck %s --check-prefix=CHECKO2
 ; RUN: %llvm2ice -Om1 --verbose none %s | FileCheck %s
 ; RUN: %llvm2ice -O2 --verbose none %s \
 ; RUN:               | llvm-mc -arch=x86 -x86-asm-syntax=intel -filetype=obj
 ; RUN: %llvm2ice -Om1 --verbose none %s \
 ; RUN:               | llvm-mc -arch=x86 -x86-asm-syntax=intel -filetype=obj
@@ skipping 70 matching lines @@
   %ptr = inttoptr i32 %iptr to i64*
   %r = call i64 @llvm.nacl.atomic.load.i64(i64* %ptr, i32 6)
   ret i64 %r
 }
 ; CHECK-LABEL: test_atomic_load_64
 ; CHECK: movq x{{.*}}, qword
 ; CHECK: movq qword {{.*}}, x{{.*}}
 
 define i32 @test_atomic_load_32_with_arith(i32 %iptr) {
 entry:
+  br label %next
+
+next:
   %ptr = inttoptr i32 %iptr to i32*
   %r = call i32 @llvm.nacl.atomic.load.i32(i32* %ptr, i32 6)
   %r2 = add i32 %r, 32
   ret i32 %r2
 }
 ; CHECK-LABEL: test_atomic_load_32_with_arith
 ; CHECK: mov {{.*}}, dword
 ; The next instruction may be a separate load or folded into an add.
+;
+; In O2 mode, we know that the load and add are going to be fused.
+; CHECKO2-LABEL: test_atomic_load_32_with_arith
+; CHECKO2: mov {{.*}}, dword
+; CHECKO2: add {{.*}}, dword
 
 define i32 @test_atomic_load_32_ignored(i32 %iptr) {
 entry:
   %ptr = inttoptr i32 %iptr to i32*
   %ignored = call i32 @llvm.nacl.atomic.load.i32(i32* %ptr, i32 6)
   ret i32 0
 }
 ; CHECK-LABEL: test_atomic_load_32_ignored
 ; CHECK: mov {{.*}}, dword
 ; CHECK: mov {{.*}}, dword
+; CHECKO2-LABEL: test_atomic_load_32_ignored
+; CHECKO2: mov {{.*}}, dword
+; CHECKO2: mov {{.*}}, dword
 
 define i64 @test_atomic_load_64_ignored(i32 %iptr) {
 entry:
   %ptr = inttoptr i32 %iptr to i64*
   %ignored = call i64 @llvm.nacl.atomic.load.i64(i64* %ptr, i32 6)
   ret i64 0
 }
 ; CHECK-LABEL: test_atomic_load_64_ignored
 ; CHECK: movq x{{.*}}, qword
 ; CHECK: movq qword {{.*}}, x{{.*}}
@@ skipping 766 matching lines @@
   ret i32 %z
 }
 ; CHECK-LABEL: test_atomic_is_lock_free_can_dce
 ; CHECK: mov {{.*}}, 1
 ; CHECK: ret
 ; CHECK: add
 ; CHECK: ret
 
 ; ERRORS-NOT: ICE translation error
 ; DUMP-NOT: SZ