[LTO] Run ObjCARCContractPass according to the callgraph (#103034)

This matches other IR codegen passes and avoids a Dominator Tree
Construction in AMDGPU O2/O3 builds.

Author: jayfoad

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -944,13 +944,13 @@ void TargetPassConfig::addCodeGenPrepare() {
 void TargetPassConfig::addISelPrepare() {
   addPreISel();
 
-  if (getOptLevel() != CodeGenOptLevel::None)
-    addPass(createObjCARCContractPass());
-
   // Force codegen to run according to the callgraph.
   if (requiresCodeGenSCCOrder())
     addPass(new DummyCGSCCPass);
 
+  if (getOptLevel() != CodeGenOptLevel::None)
+    addPass(createObjCARCContractPass());
+
   addPass(createCallBrPass());
 
   // Add both the safe stack and the stack protection passes: each of them will

llvm/test/CodeGen/AMDGPU/llc-pipeline.ll

@@ -279,15 +279,15 @@
 ; GCN-O1-NEXT:        AMDGPU Rewrite Undef for PHI
 ; GCN-O1-NEXT:        LCSSA Verifier
 ; GCN-O1-NEXT:        Loop-Closed SSA Form Pass
+; GCN-O1-NEXT:      DummyCGSCCPass
+; GCN-O1-NEXT:      FunctionPass Manager
+; GCN-O1-NEXT:        Dominator Tree Construction
 ; GCN-O1-NEXT:        Basic Alias Analysis (stateless AA impl)
 ; GCN-O1-NEXT:        Function Alias Analysis Results
 ; GCN-O1-NEXT:        ObjC ARC contraction
-; GCN-O1-NEXT:      DummyCGSCCPass
-; GCN-O1-NEXT:      FunctionPass Manager
 ; GCN-O1-NEXT:        Prepare callbr
 ; GCN-O1-NEXT:        Safe Stack instrumentation pass
 ; GCN-O1-NEXT:        Insert stack protectors
-; GCN-O1-NEXT:        Dominator Tree Construction
 ; GCN-O1-NEXT:        Cycle Info Analysis
 ; GCN-O1-NEXT:        Uniformity Analysis
 ; GCN-O1-NEXT:        Basic Alias Analysis (stateless AA impl)
@@ -574,15 +574,15 @@
 ; GCN-O1-OPTS-NEXT:        AMDGPU Rewrite Undef for PHI
 ; GCN-O1-OPTS-NEXT:        LCSSA Verifier
 ; GCN-O1-OPTS-NEXT:        Loop-Closed SSA Form Pass
+; GCN-O1-OPTS-NEXT:      DummyCGSCCPass
+; GCN-O1-OPTS-NEXT:      FunctionPass Manager
+; GCN-O1-OPTS-NEXT:        Dominator Tree Construction
 ; GCN-O1-OPTS-NEXT:        Basic Alias Analysis (stateless AA impl)
 ; GCN-O1-OPTS-NEXT:        Function Alias Analysis Results
 ; GCN-O1-OPTS-NEXT:        ObjC ARC contraction
-; GCN-O1-OPTS-NEXT:      DummyCGSCCPass
-; GCN-O1-OPTS-NEXT:      FunctionPass Manager
 ; GCN-O1-OPTS-NEXT:        Prepare callbr
 ; GCN-O1-OPTS-NEXT:        Safe Stack instrumentation pass
 ; GCN-O1-OPTS-NEXT:        Insert stack protectors
-; GCN-O1-OPTS-NEXT:        Dominator Tree Construction
 ; GCN-O1-OPTS-NEXT:        Cycle Info Analysis
 ; GCN-O1-OPTS-NEXT:        Uniformity Analysis
 ; GCN-O1-OPTS-NEXT:        Basic Alias Analysis (stateless AA impl)
@@ -882,17 +882,15 @@
 ; GCN-O2-NEXT:        LCSSA Verifier
 ; GCN-O2-NEXT:        Loop-Closed SSA Form Pass
 ; GCN-O2-NEXT:      Analysis if a function is memory bound
+; GCN-O2-NEXT:      DummyCGSCCPass
 ; GCN-O2-NEXT:      FunctionPass Manager
 ; GCN-O2-NEXT:        Dominator Tree Construction
 ; GCN-O2-NEXT:        Basic Alias Analysis (stateless AA impl)
 ; GCN-O2-NEXT:        Function Alias Analysis Results
 ; GCN-O2-NEXT:        ObjC ARC contraction
-; GCN-O2-NEXT:      DummyCGSCCPass
-; GCN-O2-NEXT:      FunctionPass Manager
 ; GCN-O2-NEXT:        Prepare callbr
 ; GCN-O2-NEXT:        Safe Stack instrumentation pass
 ; GCN-O2-NEXT:        Insert stack protectors
-; GCN-O2-NEXT:        Dominator Tree Construction
 ; GCN-O2-NEXT:        Cycle Info Analysis
 ; GCN-O2-NEXT:        Uniformity Analysis
 ; GCN-O2-NEXT:        Basic Alias Analysis (stateless AA impl)
@@ -1205,17 +1203,15 @@
 ; GCN-O3-NEXT:        LCSSA Verifier
 ; GCN-O3-NEXT:        Loop-Closed SSA Form Pass
 ; GCN-O3-NEXT:      Analysis if a function is memory bound
+; GCN-O3-NEXT:      DummyCGSCCPass
 ; GCN-O3-NEXT:      FunctionPass Manager
 ; GCN-O3-NEXT:        Dominator Tree Construction
 ; GCN-O3-NEXT:        Basic Alias Analysis (stateless AA impl)
 ; GCN-O3-NEXT:        Function Alias Analysis Results
 ; GCN-O3-NEXT:        ObjC ARC contraction
-; GCN-O3-NEXT:      DummyCGSCCPass
-; GCN-O3-NEXT:      FunctionPass Manager
 ; GCN-O3-NEXT:        Prepare callbr
 ; GCN-O3-NEXT:        Safe Stack instrumentation pass
 ; GCN-O3-NEXT:        Insert stack protectors
-; GCN-O3-NEXT:        Dominator Tree Construction
 ; GCN-O3-NEXT:        Cycle Info Analysis
 ; GCN-O3-NEXT:        Uniformity Analysis
 ; GCN-O3-NEXT:        Basic Alias Analysis (stateless AA impl)