DI: Reverse direction of subprogram -> function edge.

Previously, subprograms contained a metadata reference to the function they
described. Because most clients need to get or set a subprogram for a given
function rather than the other way around, this created unneeded inefficiency.

For example, many passes needed to call the function llvm::makeSubprogramMap()
to build a mapping from functions to subprograms, and the IR linker needed to
fix up function references in a way that caused quadratic complexity in the IR
linking phase of LTO.

This change reverses the direction of the edge by storing the subprogram as
function-level metadata and removing DISubprogram's function field.

Since this is an IR change, a bitcode upgrade has been provided.

Fixes PR23367. An upgrade script for textual IR for out-of-tree clients is
attached to the PR.

Differential Revision: http://reviews.llvm.org/D14265

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@252219 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 12 insertions, 5 deletions

diff --git a/bindings/go/llvm/DIBuilderBindings.cpp b/bindings/go/llvm/DIBuilderBindings.cpp
index e7fe8f5dde8..e767144bb32 100644
--- a/bindings/go/llvm/DIBuilderBindings.cpp
+++ b/bindings/go/llvm/DIBuilderBindings.cpp
@@ -74,13 +74,13 @@ LLVMMetadataRef LLVMDIBuilderCreateFunction(
     LLVMDIBuilderRef Dref, LLVMMetadataRef Scope, const char *Name,
     const char *LinkageName, LLVMMetadataRef File, unsigned Line,
     LLVMMetadataRef CompositeType, int IsLocalToUnit, int IsDefinition,
-    unsigned ScopeLine, unsigned Flags, int IsOptimized, LLVMValueRef Func) {
+    unsigned ScopeLine, unsigned Flags, int IsOptimized) {
   DIBuilder *D = unwrap(Dref);
   return wrap(D->createFunction(unwrap<DIScope>(Scope), Name, LinkageName,
                                 File ? unwrap<DIFile>(File) : nullptr, Line,
                                 unwrap<DISubroutineType>(CompositeType),
                                 IsLocalToUnit, IsDefinition, ScopeLine, Flags,
-                                IsOptimized, unwrap<Function>(Func)));
+                                IsOptimized));
 }
 
 LLVMMetadataRef
diff --git a/bindings/go/llvm/DIBuilderBindings.h b/bindings/go/llvm/DIBuilderBindings.h
index ef6eda15e65..f14fd0f7b5f 100644
--- a/bindings/go/llvm/DIBuilderBindings.h
+++ b/bindings/go/llvm/DIBuilderBindings.h
@@ -55,7 +55,7 @@ LLVMMetadataRef LLVMDIBuilderCreateFunction(
     LLVMDIBuilderRef D, LLVMMetadataRef Scope, const char *Name,
     const char *LinkageName, LLVMMetadataRef File, unsigned Line,
     LLVMMetadataRef CompositeType, int IsLocalToUnit, int IsDefinition,
-    unsigned ScopeLine, unsigned Flags, int IsOptimized, LLVMValueRef Function);
+    unsigned ScopeLine, unsigned Flags, int IsOptimized);
 
 LLVMMetadataRef
 LLVMDIBuilderCreateAutoVariable(LLVMDIBuilderRef D, LLVMMetadataRef Scope,
diff --git a/bindings/go/llvm/IRBindings.cpp b/bindings/go/llvm/IRBindings.cpp
index fd0cb8006a4..4308f84cc1b 100644
--- a/bindings/go/llvm/IRBindings.cpp
+++ b/bindings/go/llvm/IRBindings.cpp
@@ -98,3 +98,7 @@ void LLVMSetCurrentDebugLocation2(LLVMBuilderRef Bref, unsigned Line,
       DebugLoc::get(Line, Col, Scope ? unwrap<MDNode>(Scope) : nullptr,
                     InlinedAt ? unwrap<MDNode>(InlinedAt) : nullptr));
 }
+
+void LLVMSetSubprogram(LLVMValueRef Func, LLVMMetadataRef SP) {
+  unwrap<Function>(Func)->setSubprogram(unwrap<DISubprogram>(SP));
+}
diff --git a/bindings/go/llvm/IRBindings.h b/bindings/go/llvm/IRBindings.h
index a53e178f1e0..dcdb26eda79 100644
--- a/bindings/go/llvm/IRBindings.h
+++ b/bindings/go/llvm/IRBindings.h
@@ -55,6 +55,8 @@ void LLVMSetCurrentDebugLocation2(LLVMBuilderRef Bref, unsigned Line,
                                   unsigned Col, LLVMMetadataRef Scope,
                                   LLVMMetadataRef InlinedAt);
 
+void LLVMSetSubprogram(LLVMValueRef Fn, LLVMMetadataRef SP);
+
 #ifdef __cplusplus
 }
 
diff --git a/bindings/go/llvm/dibuilder.go b/bindings/go/llvm/dibuilder.go
index 4ec60738a7a..778c3178583 100644
--- a/bindings/go/llvm/dibuilder.go
+++ b/bindings/go/llvm/dibuilder.go
@@ -189,7 +189,6 @@ type DIFunction struct {
 	ScopeLine    int
 	Flags        int
 	Optimized    bool
-	Function     Value
 }
 
 // CreateCompileUnit creates function debug metadata.
@@ -211,7 +210,6 @@ func (d *DIBuilder) CreateFunction(diScope Metadata, f DIFunction) Metadata {
 		C.unsigned(f.ScopeLine),
 		C.unsigned(f.Flags),
 		boolToCInt(f.Optimized),
-		f.Function.C,
 	)
 	return Metadata{C: result}
 }
diff --git a/bindings/go/llvm/ir.go b/bindings/go/llvm/ir.go
index 8fcd6ec4d74..b8ea28d3a0d 100644
--- a/bindings/go/llvm/ir.go
+++ b/bindings/go/llvm/ir.go
@@ -1057,6 +1057,9 @@ func (v Value) AddTargetDependentFunctionAttr(attr, value string) {
 func (v Value) SetPersonality(p Value) {
 	C.LLVMSetPersonalityFn(v.C, p.C)
 }
+func (v Value) SetSubprogram(sp Metadata) {
+	C.LLVMSetSubprogram(v.C, sp.C)
+}
 
 // Operations on parameters
 func (v Value) ParamsCount() int { return int(C.LLVMCountParams(v.C)) }