[DebugInfo] Add special cases for copy forwarding

Author: Snowy1803

lib/SILOptimizer/Transforms/CopyForwarding.cpp

@@ -69,6 +69,7 @@
 #include "swift/SILOptimizer/PassManager/Passes.h"
 #include "swift/SILOptimizer/PassManager/Transforms.h"
 #include "swift/SILOptimizer/Utils/CFGOptUtils.h"
+#include "swift/SILOptimizer/Utils/DebugOptUtils.h"
 #include "swift/SILOptimizer/Utils/ValueLifetime.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/Statistic.h"
@@ -698,6 +699,8 @@ propagateCopy(CopyAddrInst *CopyInst) {
       SILBuilderWithScope(CurrentCopy)
           .createDestroyAddr(CurrentCopy->getLoc(), CurrentCopy->getDest());
     }
+    swift::salvageStoreDebugInfo(CurrentCopy, CurrentCopy->getSrc(),
+                                 CurrentCopy->getDest());
     CurrentCopy->eraseFromParent();
     HasChanged = true;
     ++NumCopyForward;
@@ -706,6 +709,8 @@ propagateCopy(CopyAddrInst *CopyInst) {
   // Forward propagation failed. Attempt to backward propagate.
   if (CurrentCopy->isInitializationOfDest() && backwardPropagateCopy()) {
     LLVM_DEBUG(llvm::dbgs() << "  Reversing Copy:" << *CurrentCopy);
+    swift::salvageStoreDebugInfo(CurrentCopy, CurrentCopy->getDest(),
+                                 CurrentCopy->getSrc());
     CurrentCopy->eraseFromParent();
     HasChanged = true;
     ++NumCopyBackward;
@@ -817,6 +822,9 @@ forwardDeadTempCopy(CopyAddrInst *destCopy) {
       .createDestroyAddr(srcCopy->getLoc(), srcCopy->getDest());
   }
 
+  // Salvage debug values
+  swift::salvageStoreDebugInfo(srcCopy, srcCopy->getSrc(), srcCopy->getDest());
+
   // Delete all dead debug_value instructions
   for (auto *deadDebugUser : debugInstsToDelete) {
     deadDebugUser->eraseFromParent();
@@ -1061,9 +1069,13 @@ bool CopyForwarding::forwardPropagateCopy() {
   // Now that a deinit was found, it is safe to substitute all recorded uses
   // with the copy's source.
   for (auto *Oper : ValueUses) {
-    Oper->set(CurrentCopy->getSrc());
-    if (isa<CopyAddrInst>(Oper->getUser()))
+    if (isa<CopyAddrInst>(Oper->getUser())) {
       HasForwardedToCopy = true;
+      // This instruction gets "replaced", so we need to salvage its previous
+      // debug info
+//      swift::salvageDebugInfo(Oper->getUser());
+    }
+    Oper->set(CurrentCopy->getSrc());
   }
   return true;
 }
@@ -1190,9 +1202,13 @@ bool CopyForwarding::backwardPropagateCopy() {
   // Now that an init was found, it is safe to substitute all recorded uses
   // with the copy's dest.
   for (auto *Oper : ValueUses) {
-    Oper->set(CurrentCopy->getDest());
-    if (isa<CopyAddrInst>(Oper->getUser()))
+    if (auto *SI = dyn_cast<CopyAddrInst>(Oper->getUser())) {
       HasForwardedToCopy = true;
+      // This instruction gets "replaced", so we need to salvage its previous
+      // debug info
+      swift::salvageStoreDebugInfo(SI, SI->getSrc(), SI->getDest());
+    }
+    Oper->set(CurrentCopy->getDest());
   }
   return true;
 }

test/DebugInfo/copyforward.sil

@@ -0,0 +1,56 @@
+// RUN: %target-sil-opt -enable-sil-verify-all -sil-print-debuginfo -copy-forwarding %s | %FileCheck %s
+sil_stage canonical
+
+import Builtin
+import Swift
+
+sil_scope 1 { loc "backward.swift":66:24 parent @backward : $@convention(method) <τ_0_0> (@inout CollectionOfOne<τ_0_0>.Iterator) -> @out Optional<τ_0_0> }
+sil_scope 2 { loc "backward.swift":67:9 parent 1 }
+
+// CHECK-LABEL: sil {{.+}} @backward
+sil [serialized] [ossa] @backward : $@convention(method) <Element> (@inout CollectionOfOne<Element>.Iterator) -> @out Optional<Element> {
+[%0: write v**]
+[%1: read s0.v**, write s0.v**, copy s0.v**, destroy s0.v**]
+[global: read,write,copy,destroy,allocate,deinit_barrier]
+bb0(%0 : $*Optional<Element>, %1 : $*CollectionOfOne<Element>.Iterator):
+  debug_value %1 : $*CollectionOfOne<Element>.Iterator, var, name "self", argno 1, expr op_deref, loc "backward.swift":66:24, scope 1
+  %3 = alloc_stack [lexical] [var_decl] $Optional<Element>, let, name "result", loc "backward.swift":67:9, scope 2
+  %4 = struct_element_addr %1 : $*CollectionOfOne<Element>.Iterator, #CollectionOfOne.Iterator._elements, loc "backward.swift":67:18, scope 1
+
+  // CHECK: debug_value %{{[0-9]+}} : $*Optional<Element>, let, (name "result", loc "backward.swift":67:9, scope 2), loc "backward.swift":67:18, scope 2
+
+  copy_addr %4 to [init] %3 : $*Optional<Element>, loc "backward.swift":67:18, scope 1
+  %6 = alloc_stack $Optional<Element>, loc "backward.swift":68:17, scope 2
+  inject_enum_addr %6 : $*Optional<Element>, #Optional.none!enumelt, loc "backward.swift":68:17, scope 2
+  %8 = struct_element_addr %1 : $*CollectionOfOne<Element>.Iterator, #CollectionOfOne.Iterator._elements, loc "backward.swift":68:15, scope 2
+  copy_addr [take] %6 to %8 : $*Optional<Element>, loc "backward.swift":68:15, scope 2
+  dealloc_stack %6 : $*Optional<Element>, loc "backward.swift":68:17, scope 2
+  copy_addr [take] %3 to [init] %0 : $*Optional<Element>, loc "backward.swift":69:12, scope 2
+  dealloc_stack %3 : $*Optional<Element>, loc "backward.swift":70:3, scope 2
+  %13 = tuple (), loc "backward.swift":70:3, scope 2
+  return %13 : $(), loc "backward.swift":69:5, scope 2
+} // end sil function 'backward'
+
+sil_scope 10 { loc "tempcopy.swift":714:27 parent @tempcopy : $@convention(method) <τ_0_0 where τ_0_0 : Strideable, τ_0_0.Stride : SignedInteger> (@in PartialRangeFrom<τ_0_0>) -> @out PartialRangeFrom<τ_0_0>.Iterator }
+sil_scope 12 { loc "tempcopy.swift":715:12 parent 10 }
+
+// CHECK-LABEL: sil {{.+}} @tempcopy
+sil [serialized] [ossa] @tempcopy : $@convention(method) <Bound where Bound : Strideable, Bound.Stride : SignedInteger> (@in PartialRangeFrom<Bound>) -> @out PartialRangeFrom<Bound>.Iterator {
+[%0: write v**]
+[%1: read v**, write v**, copy s0.v**, destroy v**]
+[global: read,write,copy,destroy,allocate,deinit_barrier]
+bb0(%0 : $*PartialRangeFrom<Bound>.Iterator, %1 : $*PartialRangeFrom<Bound>):
+  debug_value %1 : $*PartialRangeFrom<Bound>, let, name "self", argno 1, expr op_deref, loc "tempcopy.swift":714:27, scope 10 // id: %2
+  %3 = struct_element_addr %1 : $*PartialRangeFrom<Bound>, #PartialRangeFrom.lowerBound, loc "tempcopy.swift":715:31, scope 10 // user: %5
+  %4 = alloc_stack $Bound, loc "tempcopy.swift":715:31, scope 10 // users: %8, %6, %10, %5
+  copy_addr [take] %3 to [init] %4 : $*Bound, loc "tempcopy.swift":715:31, scope 10 // id: %5
+  // CHECK: debug_value %{{[0-9]+}} : $*Bound, let, (name "_current", loc "tempcopy.swift":696:17
+  // CHECK-SAME:   expr op_deref, loc "tempcopy.swift":715:31
+  debug_value %4 : $*Bound, let, name "_current", expr op_deref, loc "tempcopy.swift":696:17, scope 12 // id: %6
+  %7 = struct_element_addr %0 : $*PartialRangeFrom<Bound>.Iterator, #PartialRangeFrom.Iterator._current, loc "tempcopy.swift":696:50, scope 12 // user: %8
+  copy_addr [take] %4 to [init] %7 : $*Bound, loc "tempcopy.swift":696:50, scope 12 // id: %8
+  %9 = tuple (), loc * "tempcopy.swift":696:61, scope 12
+  dealloc_stack %4 : $*Bound, loc "tempcopy.swift":715:41, scope 10 // id: %10
+  %11 = tuple (), loc "tempcopy.swift":716:3, scope 10 // user: %12
+  return %11 : $(), loc "tempcopy.swift":715:5, scope 10 // id: %12
+} // end sil function 'tempcopy'

test/SILOptimizer/copyforward_ossa.sil

@@ -284,7 +284,7 @@ public struct S<T> {
 // CHECK-LABEL: sil [ossa] @deadtemp :
 // CHECK: %[[G:.*]] = struct_element_addr %0 : $*S<T>, #S.g
 // CHECK-NOT: copy_addr
-// CHECK-NOT: debug_value {{.*}} expr op_deref
+// CHECK: debug_value %[[G:.*]] : $*T, expr op_deref
 // CHECK: %[[F:.*]] = struct_element_addr %0 : $*S<T>, #S.f
 // CHECK: copy_addr %[[G]] to %[[F]] : $*T
 // CHECK-LABEL: } // end sil function 'deadtemp'