Fix SplitHugeSwitchPass off-by-one

Summary: The determination to split and the computation of splits should match. Reviewed By: thezhangwei Differential Revision: D45091645 fbshipit-source-id: 9179dbfab61cedbeefaae8f139f23e482169b835
facebook · Apr 18, 2023 · f8953b5 · f8953b5
1 parent e18a3e1
commit f8953b5
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/opt/split_huge_switches/SplitHugeSwitchPass.cpp b/opt/split_huge_switches/SplitHugeSwitchPass.cpp
@@ -523,7 +523,7 @@ AnalysisData analyze(DexMethod* m,
   data.no_code = false;
 
   auto size = code->sum_opcode_sizes();
-  if (size < insn_threshold) {
+  if (size <= insn_threshold) {
     data.under_insn_threshold = true;
     return data;
   }
@@ -555,6 +555,7 @@ AnalysisData analyze(DexMethod* m,
   data.no_easy_expr = false;
 
   size_t nr_splits = (size_t)std::ceil(((float)size) / insn_threshold);
+  redex_assert(nr_splits > 1);
   auto switch_range =
       get_switch_range(*scoped_cfg, switch_it.block(), nr_splits);
   if (switch_range.cases < nr_splits) {

diff --git a/test/unit/SplitHugeSwitchTest.cpp b/test/unit/SplitHugeSwitchTest.cpp
@@ -468,3 +468,14 @@ TEST_F(SplitHugeSwitchTest, Split3) {
                   });
   EXPECT_TRUE(res);
 }
+
+TEST_F(SplitHugeSwitchTest, NoSplitExactThreshold) {
+  auto res = test("(I)V",
+                  SRC,
+                  28,
+                  0,
+                  method_profiles::MethodProfiles(),
+                  0.0,
+                  {pair("", SRC)});
+  EXPECT_TRUE(res);
+}