Enable mandatory copy propagation SIL pass.

This shortens -Onone lifetimes.

To eliminate ARC traffic, the optimizer reorders object
destruction. This changes observable program behavior. If a custom
deinitializer produces side effects, code may observe those side
effects earlier after optimization. Similarly, code that dereferences
a weak reference may observe a 'nil' reference after optimization,
while the unoptimized code observed a valid object.

Developers have overwhelmingly requested that object lifetimes have
similar behavior in -Onone and -O builds in order to find and diagnose
program bugs involving weak references and other lifetime assumptions.

Enabling the copy propagation at -Onone is simply a matter of flipping
a switch. -Onone runtime and code size will improve. By design, copy
propagation, has no direct affect on compile time. It will indirectly
improve optimized compile times, but in debug builds, it simply isn't
a factor.

To support debugging, a "poison" flag was (in prior commits) added to
new destroy_value instructions generated by copy propagation.  When
OwnershipModelEliminator lowers destroy_value [poison] it will
generate new debug_value instructions with a “poison” flag.

These additional poison stores to the stack could increase both code
size and -Onone runtime.

rdar://75012368 (-Onone compiler support for early object deinitialization with sentinel dead references)

Author: atrick

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -845,7 +845,7 @@ SILPassPipelinePlan::getOnonePassPipeline(const SILOptions &Options) {
   P.startPipeline("non-Diagnostic Enabling Mandatory Optimizations");
   P.addForEachLoopUnroll();
   P.addMandatoryCombine();
-  if (P.getOptions().EnableCopyPropagation) {
+  if (!P.getOptions().DisableCopyPropagation) {
     // MandatoryCopyPropagation should only be run at -Onone, not -O.
     P.addMandatoryCopyPropagation();
   }

test/IRGen/unmanaged_objc_throw_func.swift

@@ -36,12 +36,16 @@ import Foundation
 
 // CHECK: [[L2]]:                                     ; preds = %entry
 // CHECK-NEXT: %[[T4:.+]] = phi %TSo10CFArrayRefa* [ %[[T0]], %entry ]
+// CHECK-NEXT: %[[T4a:.+]] = bitcast %T25unmanaged_objc_throw_func9SR_9035_CC* %{{.+}} to i8*
+// CHECK-NEXT: call void @llvm.objc.release(i8* %[[T4a]])
 // CHECK-NEXT: %[[T5:.+]] = ptrtoint %TSo10CFArrayRefa* %[[T4]] to i{{32|64}}
 // CHECK-NEXT: br label %[[L3:.+]]
 
 // CHECK: [[L1]]:                                     ; preds = %entry
 // CHECK-NEXT: %[[T6:.+]] = phi %swift.error* [ %[[T2]], %entry ]
 // CHECK-NEXT: store %swift.error* null, %swift.error** %swifterror, align {{[0-9]+}}
+// CHECK-NEXT: %[[T6a:.+]] = bitcast %T25unmanaged_objc_throw_func9SR_9035_CC* %{{.+}} to i8*
+// CHECK-NEXT: call void @llvm.objc.release(i8* %[[T6a]])
 // CHECK-NEXT: %[[T7:.+]] = icmp eq i{{32|64}} %{{.+}}, 0
 // CHECK-NEXT: br i1 %[[T7]], label %[[L4:.+]], label %[[L5:.+]]
 
@@ -66,7 +70,5 @@ import Foundation
 
 // CHECK: [[L3]]:                                     ; preds = %[[L2]], %[[L7]]
 // CHECK-NEXT: %[[T12:.+]] = phi i{{32|64}} [ 0, %[[L7]] ], [ %[[T5]], %[[L2]] ]
-// CHECK-NEXT: %[[T13:.+]] = bitcast %T25unmanaged_objc_throw_func9SR_9035_CC* %{{.+}} to i8*
-// CHECK-NEXT: call void @llvm.objc.release(i8* %[[T13]])
 // CHECK-NEXT: %[[T14:.+]] = inttoptr i{{32|64}} %[[T12]] to %struct.__CFArray*
 // CHECK-NEXT: ret %struct.__CFArray* %[[T14]]

test/Interpreter/builtin_bridge_object.swift

@@ -65,6 +65,7 @@ if true {
   // CHECK-NEXT: true
   print(x === x2)
   // CHECK-OPT-NEXT: deallocated
+  // CHECK-DBG-NEXT: deallocated
 
   print(nonPointerBits(bo) == 0)
   // CHECK-NEXT: true
@@ -78,7 +79,6 @@ if true {
   _fixLifetime(bo3)
   _fixLifetime(bo4)
 }
-// CHECK-DBG-NEXT: deallocated
 // CHECK-NEXT: deallocated
 
 // Try with all spare bits set.
@@ -94,6 +94,7 @@ if true {
   // CHECK-NEXT: true
   print(x === x2)
   // CHECK-OPT-NEXT: deallocated
+  // CHECK-DBG-NEXT: deallocated
 
   print(nonPointerBits(bo) == NATIVE_SPARE_BITS)
   // CHECK-NEXT: true
@@ -107,7 +108,6 @@ if true {
   _fixLifetime(bo3)
   _fixLifetime(bo4)
 }
-// CHECK-DBG-NEXT: deallocated
 // CHECK-NEXT: deallocated
 
 

test/sil-passpipeline-dump/basic.test-sh

@@ -2,7 +2,8 @@
 
 // CHECK: ---
 // CHECK: name:            non-Diagnostic Enabling Mandatory Optimizations
-// CHECK: passes:          [ "for-each-loop-unroll", "mandatory-combine", "mandatory-arc-opts" ]
+// CHECK: passes:          [ "for-each-loop-unroll", "mandatory-combine", "mandatory-copy-propagation",
+// CHECK:                    "mandatory-arc-opts" ]
 // CHECK: ---
 // CHECK: name:            Serialization
 // CHECK: passes:          [ "serialize-sil", "ownership-model-eliminator" ]