[Incremental] Don't read swiftdeps of a new input or of a crashed compile.

Sources/SwiftDriver/Incremental Compilation/BuildRecord.swift

@@ -69,6 +69,10 @@ public struct BuildRecord {
 
     var serializedName: String { rawValue }
   }
+
+  var allInputs: Set<VirtualPath> {
+    Set( inputInfos.map {$0.key} )
+  }
 }
 
 // MARK: - Reading the old map and deciding whether to use it

Sources/SwiftDriver/Incremental Compilation/IncrementalCompilationState.swift

@@ -95,6 +95,7 @@ public class IncrementalCompilationState {
             ModuleDependencyGraph.buildInitialGraph(
               diagnosticEngine: diagnosticEngine,
               inputs: buildRecordInfo.compilationInputModificationDates.keys,
+              previousInputs: outOfDateBuildRecord.allInputs,
               outputFileMap: outputFileMap,
               parsedOptions: &parsedOptions,
               remarkDisabled: Diagnostic.Message.remark_incremental_compilation_disabled,

Sources/SwiftDriver/Incremental Compilation/ModuleDependencyGraph.swift

@@ -55,6 +55,7 @@ extension ModuleDependencyGraph {
   static func buildInitialGraph<Inputs: Sequence>(
     diagnosticEngine: DiagnosticsEngine,
     inputs: Inputs,
+    previousInputs: Set<VirtualPath>,
     outputFileMap: OutputFileMap?,
     parsedOptions: inout ParsedOptions,
     remarkDisabled: (String) -> Diagnostic.Message,
@@ -81,22 +82,27 @@ extension ModuleDependencyGraph {
       )
       return nil
     }
-    let inputsWithUnreadableSwiftDeps = inputsAndSwiftdeps.compactMap {
+    let previousInputsWithMalformedSwiftDeps = inputsAndSwiftdeps.compactMap {
       input, swiftDepsFile -> (TypedVirtualPath, VirtualPath)? in
       guard let swiftDepsFile = swiftDepsFile
       else {
         return nil
       }
       let swiftDeps = SwiftDeps(swiftDepsFile)
       graph.sourceSwiftDepsMap[input] = swiftDeps
+      guard previousInputs.contains(input.file)
+      else {
+        // do not try to read swiftdeps of a new input
+        return nil
+      }
       let changes = Integrator.integrate(swiftDeps: swiftDeps,
                                          into: graph,
                                          input: input,
                                          reportIncrementalDecision: reportIncrementalDecision,
                                          diagnosticEngine: diagnosticEngine)
       return changes == nil ? (input, swiftDepsFile) : nil
     }
-    return (graph, inputsWithUnreadableSwiftDeps)
+    return (graph, previousInputsWithMalformedSwiftDeps)
   }
 }
 // MARK: - Scheduling the first wave

Sources/SwiftDriverExecution/MultiJobExecutor.swift

@@ -533,7 +533,9 @@ class ExecuteJobRule: LLBuildRule {
 #endif
         }
       }
-      context.addRuleBeyondMandatoryCompiles(finishedJob: job, result: result)
+      if case .terminated = result.exitStatus {
+        context.addRuleBeyondMandatoryCompiles(finishedJob: job, result: result)
+      }
 
       // Inform the delegate about job finishing.
       context.delegateQueue.async {