Shift DCE pass to optimize imaging mode code better (#50631)

pchintalapudi · web-flow · commit e23e1168a27e · 2023-07-23T17:27:17.000Z
diff --git a/src/pipeline.cpp b/src/pipeline.cpp
@@ -342,9 +342,12 @@ static void buildEarlySimplificationPipeline(ModulePassManager &MPM, PassBuilder
         if (O.getSpeedupLevel() >= 2) {
             JULIA_PASS(FPM.addPass(PropagateJuliaAddrspacesPass()));
         }
+        // DCE must come before simplifycfg
+        // codegen can generate unused statements when generating builtin calls,
+        // and those dead statements can alter how simplifycfg optimizes the CFG
+        FPM.addPass(DCEPass());
         FPM.addPass(SimplifyCFGPass(basicSimplifyCFGOptions()));
         if (O.getSpeedupLevel() >= 1) {
-            FPM.addPass(DCEPass());
             FPM.addPass(SROAPass());
         }
         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));

Original file line number	Diff line number	Diff line change
`@@ -342,9 +342,12 @@ static void buildEarlySimplificationPipeline(ModulePassManager &MPM, PassBuilder`
`342`	`342`	`if (O.getSpeedupLevel() >= 2) {`
`343`	`343`	`JULIA_PASS(FPM.addPass(PropagateJuliaAddrspacesPass()));`
`344`	`344`	`}`
	`345`	`+ // DCE must come before simplifycfg`
	`346`	`+ // codegen can generate unused statements when generating builtin calls,`
	`347`	`+ // and those dead statements can alter how simplifycfg optimizes the CFG`
	`348`	`+ FPM.addPass(DCEPass());`
`345`	`349`	`FPM.addPass(SimplifyCFGPass(basicSimplifyCFGOptions()));`
`346`	`350`	`if (O.getSpeedupLevel() >= 1) {`
`347`		`- FPM.addPass(DCEPass());`
`348`	`351`	`FPM.addPass(SROAPass());`
`349`	`352`	`}`
`350`	`353`	`MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));`