diff mbox series

Go patch committed: Support new language constructs in escape analysis

Message ID CAOyqgcWquhCx9aPB7L_HVFMbhnuww5ssLyOkKWyz7R7qbLkmqw@mail.gmail.com
State New
Headers show
Series Go patch committed: Support new language constructs in escape analysis | expand

Commit Message

Ian Lance Taylor Aug. 4, 2021, 1:32 a.m. UTC
This Go frontend patch by Cherry Mui supports the new language
constructs in escape analysis.  Previous patches added new language
constructs in Go 1.17, specifically, unsafe.Add, unsafe.Slice, and
conversion from a slice to a pointer
to an array. This patch handles them in the escape analysis.

At the point of the escape analysis, unsafe.Add and unsafe.Slice are
still builtin calls, so just handle them in data flow.  Conversion
from a slice to a pointer to an array has already been lowered to a
combination of compound expression, conditional expression and slice
info expressions, so handle them in the escape analysis.

Bootstrapped and ran Go testsuite on x86_64-pc-linux-gnu.  Committed
to mainline.

Ian
98b3c98f4acd7d6f74d0f6ad592a7623ebafecd4
diff mbox series

Patch

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index 5a097ffee85..be1a90f7aa1 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@ 
-2031f0be9c0b5fda6421d290a0261eb6bd1c8205
+616ee658a6238e7de53592ebda5997f6de6a00de
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/escape.cc b/gcc/go/gofrontend/escape.cc
index cf688740443..347ac2534c9 100644
--- a/gcc/go/gofrontend/escape.cc
+++ b/gcc/go/gofrontend/escape.cc
@@ -2325,19 +2325,55 @@  Escape_analysis_assign::assign(Node* dst, Node* src)
 	  }
 	  break;
 
+        case Expression::EXPRESSION_SLICE_INFO:
+          {
+            Slice_info_expression* sie = e->slice_info_expression();
+            if (sie->info() == Expression::SLICE_INFO_VALUE_POINTER)
+              {
+                Node* slice = Node::make_node(sie->slice());
+                this->assign(dst, slice);
+              }
+          }
+          break;
+
 	case Expression::EXPRESSION_CALL:
 	  {
 	    Call_expression* call = e->call_expression();
             if (call->is_builtin())
               {
                 Builtin_call_expression* bce = call->builtin_call_expression();
-                if (bce->code() == Builtin_call_expression::BUILTIN_APPEND)
+                switch (bce->code())
                   {
-                    // Append returns the first argument.
-                    // The subsequent arguments are already leaked because
-                    // they are operands to append.
-                    Node* appendee = Node::make_node(call->args()->front());
-                    this->assign(dst, appendee);
+                  case Builtin_call_expression::BUILTIN_APPEND:
+                    {
+                      // Append returns the first argument.
+                      // The subsequent arguments are already leaked because
+                      // they are operands to append.
+                      Node* appendee = Node::make_node(call->args()->front());
+                      this->assign(dst, appendee);
+                    }
+                    break;
+
+                  case Builtin_call_expression::BUILTIN_ADD:
+                    {
+                      // unsafe.Add(p, off).
+                      // Flow p to result.
+                      Node* arg = Node::make_node(call->args()->front());
+                      this->assign(dst, arg);
+                    }
+                    break;
+
+                  case Builtin_call_expression::BUILTIN_SLICE:
+                    {
+                      // unsafe.Slice(p, len).
+                      // The resulting slice has the same backing store as p. Flow p to result.
+                      Node* arg = Node::make_node(call->args()->front());
+                      this->assign(dst, arg);
+                    }
+                    break;
+
+                  default:
+                    break;
                   }
                 break;
               }
@@ -2592,6 +2628,21 @@  Escape_analysis_assign::assign(Node* dst, Node* src)
 	  }
 	  break;
 
+        case Expression::EXPRESSION_CONDITIONAL:
+          {
+            Conditional_expression* ce = e->conditional_expression();
+            this->assign(dst, Node::make_node(ce->then_expr()));
+            this->assign(dst, Node::make_node(ce->else_expr()));
+          }
+          break;
+
+        case Expression::EXPRESSION_COMPOUND:
+          {
+            Compound_expression* ce = e->compound_expression();
+            this->assign(dst, Node::make_node(ce->expr()));
+          }
+          break;
+
 	default:
 	  // TODO(cmang): Add debug info here; this should not be reachable.
 	  // For now, just to be conservative, we'll just say dst flows to src.
diff --git a/gcc/go/gofrontend/expressions.cc b/gcc/go/gofrontend/expressions.cc
index 51a8b7e4322..3e433d6c20d 100644
--- a/gcc/go/gofrontend/expressions.cc
+++ b/gcc/go/gofrontend/expressions.cc
@@ -18009,49 +18009,7 @@  Expression::make_type_info(Type* type, Type_info type_info)
   return new Type_info_expression(type, type_info);
 }
 
-// An expression that evaluates to some characteristic of a slice.
-// This is used when indexing, bound-checking, or nil checking a slice.
-
-class Slice_info_expression : public Expression
-{
- public:
-  Slice_info_expression(Expression* slice, Slice_info slice_info,
-                        Location location)
-    : Expression(EXPRESSION_SLICE_INFO, location),
-      slice_(slice), slice_info_(slice_info)
-  { }
-
- protected:
-  Type*
-  do_type();
-
-  void
-  do_determine_type(const Type_context*)
-  { }
-
-  Expression*
-  do_copy()
-  {
-    return new Slice_info_expression(this->slice_->copy(), this->slice_info_,
-                                     this->location());
-  }
-
-  Bexpression*
-  do_get_backend(Translate_context* context);
-
-  void
-  do_dump_expression(Ast_dump_context*) const;
-
-  void
-  do_issue_nil_check()
-  { this->slice_->issue_nil_check(); }
-
- private:
-  // The slice for which we are getting information.
-  Expression* slice_;
-  // What information we want.
-  Slice_info slice_info_;
-};
+// Slice_info_expression.
 
 // Return the type of the slice info.
 
diff --git a/gcc/go/gofrontend/expressions.h b/gcc/go/gofrontend/expressions.h
index 492849bb33e..79a8785b69d 100644
--- a/gcc/go/gofrontend/expressions.h
+++ b/gcc/go/gofrontend/expressions.h
@@ -62,6 +62,7 @@  class Type_guard_expression;
 class Heap_expression;
 class Receive_expression;
 class Slice_value_expression;
+class Slice_info_expression;
 class Conditional_expression;
 class Compound_expression;
 class Numeric_constant;
@@ -900,6 +901,14 @@  class Expression
   compound_expression()
   { return this->convert<Compound_expression, EXPRESSION_COMPOUND>(); }
 
+  // If this is a slice info expression, return the
+  // Slice_info_expression structure.  Otherwise, return NULL.
+  Slice_info_expression*
+  slice_info_expression()
+  {
+    return this->convert<Slice_info_expression, EXPRESSION_SLICE_INFO>();
+  }
+
   // Return true if this is a composite literal.
   bool
   is_composite_literal() const;
@@ -4262,6 +4271,60 @@  class Slice_value_expression : public Expression
   Expression* cap_;
 };
 
+// An expression that evaluates to some characteristic of a slice.
+// This is used when indexing, bound-checking, or nil checking a slice.
+
+class Slice_info_expression : public Expression
+{
+ public:
+  Slice_info_expression(Expression* slice, Slice_info slice_info,
+                        Location location)
+    : Expression(EXPRESSION_SLICE_INFO, location),
+      slice_(slice), slice_info_(slice_info)
+  { }
+
+  // The slice operand of this slice info expression.
+  Expression*
+  slice() const
+  { return this->slice_; }
+
+  // The info this expression is about.
+  Slice_info
+  info() const
+  { return this->slice_info_; }
+
+ protected:
+  Type*
+  do_type();
+
+  void
+  do_determine_type(const Type_context*)
+  { }
+
+  Expression*
+  do_copy()
+  {
+    return new Slice_info_expression(this->slice_->copy(), this->slice_info_,
+                                     this->location());
+  }
+
+  Bexpression*
+  do_get_backend(Translate_context* context);
+
+  void
+  do_dump_expression(Ast_dump_context*) const;
+
+  void
+  do_issue_nil_check()
+  { this->slice_->issue_nil_check(); }
+
+ private:
+  // The slice for which we are getting information.
+  Expression* slice_;
+  // What information we want.
+  Slice_info slice_info_;
+};
+
 // Conditional expressions.
 
 class Conditional_expression : public Expression
@@ -4277,6 +4340,14 @@  class Conditional_expression : public Expression
   condition() const
   { return this->cond_; }
 
+  Expression*
+  then_expr() const
+  { return this->then_; }
+
+  Expression*
+  else_expr() const
+  { return this->else_; }
+
  protected:
   int
   do_traverse(Traverse*);
@@ -4322,6 +4393,10 @@  class Compound_expression : public Expression
   init() const
   { return this->init_; }
 
+  Expression*
+  expr() const
+  { return this->expr_; }
+
  protected:
   int
   do_traverse(Traverse*);