[PATCH] ubsan: Only emit constants for filenames and type descriptors once.

[Will Dietz]

Produces neater IR in significantly less time.

(~18% faster -O0 compile time for sqlite3 with -fsanitize=undefined)
-----

Patch attached, both of these were marked as FIXME's previously.

Okay to commit?

~Will

From eb61ff9d5f83be6d828ed0769732bb06d8478a19 Mon Sep 17 00:00:00 2001
From: Will Dietz <w...@wdtz.org>
Date: Thu, 7 Nov 2013 15:27:03 -0600
Subject: [PATCH] ubsan: Only emit constants for filenames and type descriptors
 once.

Produces neater IR in significantly less time.

(~18% faster -O0 compile time for sqlite3 with -fsanitize=undefined)
---
 lib/CodeGen/CGExpr.cpp                  | 13 +++++++++----
 lib/CodeGen/CodeGenModule.h             | 10 ++++++++++
 test/CodeGen/compound-assign-overflow.c |  3 +--
 3 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 96d6a01..be50f4e 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -2027,7 +2027,10 @@ LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
 /// followed by an array of i8 containing the type name. TypeKind is 0 for an
 /// integer, 1 for a floating point value, and -1 for anything else.
 llvm::Constant *CodeGenFunction::EmitCheckTypeDescriptor(QualType T) {
-  // FIXME: Only emit each type's descriptor once.
+  // Only emit each type's descriptor once.
+  if (llvm::Constant *C = CGM.getTypeDescriptor(T))
+    return C;
+
   uint16_t TypeKind = -1;
   uint16_t TypeInfo = 0;
 
@@ -2060,6 +2063,10 @@ llvm::Constant *CodeGenFunction::EmitCheckTypeDescriptor(QualType T) {
                              llvm::GlobalVariable::PrivateLinkage,
                              Descriptor);
   GV->setUnnamedAddr(true);
+
+  // Remember the descriptor for this type.
+  CGM.setTypeDescriptor(T, GV);
+
   return GV;
 }
 
@@ -2102,9 +2109,7 @@ llvm::Constant *CodeGenFunction::EmitCheckSourceLocation(SourceLocation Loc) {
   PresumedLoc PLoc = getContext().getSourceManager().getPresumedLoc(Loc);
 
   llvm::Constant *Data[] = {
-    // FIXME: Only emit each file name once.
-    PLoc.isValid() ? cast<llvm::Constant>(
-                       Builder.CreateGlobalStringPtr(PLoc.getFilename()))
+    PLoc.isValid() ? CGM.GetAddrOfConstantCString(PLoc.getFilename(), ".src")
                    : llvm::Constant::getNullValue(Int8PtrTy),
     Builder.getInt32(PLoc.isValid() ? PLoc.getLine() : 0),
     Builder.getInt32(PLoc.isValid() ? PLoc.getColumn() : 0)
diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 02b9ce6..c161224 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -318,6 +318,9 @@ class CodeGenModule : public CodeGenTypeCache {
   llvm::DenseMap<QualType, llvm::Constant *> AtomicSetterHelperFnMap;
   llvm::DenseMap<QualType, llvm::Constant *> AtomicGetterHelperFnMap;
 
+  /// Map used to get unique type descriptor constants for sanitizers.
+  llvm::DenseMap<QualType, llvm::Constant *> TypeDescriptorMap;
+
   /// Map used to track internal linkage functions declared within
   /// extern "C" regions.
   typedef llvm::MapVector<IdentifierInfo *,
@@ -498,6 +501,13 @@ public:
     AtomicGetterHelperFnMap[Ty] = Fn;
   }
 
+  llvm::Constant *getTypeDescriptor(QualType Ty) {
+    return TypeDescriptorMap[Ty];
+  }
+  void setTypeDescriptor(QualType Ty, llvm::Constant *C) {
+    TypeDescriptorMap[Ty] = C;
+  }
+
   CGDebugInfo *getModuleDebugInfo() { return DebugInfo; }
 
   llvm::MDNode *getNoObjCARCExceptionsMetadata() {
diff --git a/test/CodeGen/compound-assign-overflow.c b/test/CodeGen/compound-assign-overflow.c
index e82061b..1533429 100644
--- a/test/CodeGen/compound-assign-overflow.c
+++ b/test/CodeGen/compound-assign-overflow.c
@@ -7,8 +7,7 @@
 // CHECK: @[[LINE_100:.*]] = private unnamed_addr global {{.*}}, i32 100, i32 5 {{.*}} @[[INT]]
 // CHECK: @[[UINT:.*]] = private unnamed_addr constant { i16, i16, [15 x i8] } { i16 0, i16 10, [15 x i8] c"'unsigned int'\00" }
 // CHECK: @[[LINE_200:.*]] = private unnamed_addr global {{.*}}, i32 200, i32 5 {{.*}} @[[UINT]]
-// CHECK: @[[DIVINT:.*]] = private unnamed_addr constant { i16, i16, [6 x i8] } { i16 0, i16 11, [6 x i8] c"'int'\00" }
-// CHECK: @[[LINE_300:.*]] = private unnamed_addr global {{.*}}, i32 300, i32 5 {{.*}} @[[DIVINT]]
+// CHECK: @[[LINE_300:.*]] = private unnamed_addr global {{.*}}, i32 300, i32 5 {{.*}} @[[INT]]
 
 int32_t x;
 
-- 
1.8.4.2


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