Fix __builtin_assume_aligned with too large values.

Code to handle __builtin_assume_aligned was allowing larger values, but
would convert this to unsigned along the way. This patch removes the
EmitAssumeAligned overloads that take unsigned to do away with this
problem.

Additionally, it adds a warning that values greater than 1 <<29 are
ignored by LLVM.

Differential Revision: https://reviews.llvm.org/D68824

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374450 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index bcd059be9113955fbd68fe484c93c168423613bd..68f2b379507be1ac68dee09ed9ed7669940ae4be 100644 (file)
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -2853,6 +2853,10 @@ def err_alignment_dependent_typedef_name : Error<
 
 def err_attribute_aligned_too_great : Error<
   "requested alignment must be %0 bytes or smaller">;
+def warn_assume_aligned_too_great
+    : Warning<"requested alignment must be %0 bytes or smaller; assumption "
+              "ignored">,
+      InGroup<DiagGroup<"builtin-assume-aligned-alignment">>;
 def warn_redeclaration_without_attribute_prev_attribute_ignored : Warning<
   "%q0 redeclared without %1 attribute: previous %1 ignored">,
   InGroup<MicrosoftInconsistentDllImport>;

diff --git a/lib/CodeGen/CGBuiltin.cpp b/lib/CodeGen/CGBuiltin.cpp
index 0562a623ae2b3eff62f42bf1447d71a53f87e43e..e6369d80cd73cb0f5a7c092fe943b81a8a943f16 100644 (file)
--- a/lib/CodeGen/CGBuiltin.cpp
+++ b/lib/CodeGen/CGBuiltin.cpp
@@ -2048,11 +2048,10 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
 
     Value *AlignmentValue = EmitScalarExpr(E->getArg(1));
     ConstantInt *AlignmentCI = cast<ConstantInt>(AlignmentValue);
-    unsigned Alignment = (unsigned)AlignmentCI->getZExtValue();
 
     EmitAlignmentAssumption(PtrValue, Ptr,
                             /*The expr loc is sufficient.*/ SourceLocation(),
-                            Alignment, OffsetValue);
+                            AlignmentCI, OffsetValue);
     return RValue::get(PtrValue);
   }
   case Builtin::BI__assume:

diff --git a/lib/CodeGen/CGCall.cpp b/lib/CodeGen/CGCall.cpp
index 682a7ccb493f515c9c575170e4becbc614aa6baf..2ec9e91e3154795e6069fce2e922f782d0ec3a87 100644 (file)
--- a/lib/CodeGen/CGCall.cpp
+++ b/lib/CodeGen/CGCall.cpp
@@ -4569,7 +4569,7 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
       llvm::Value *Alignment = EmitScalarExpr(AA->getAlignment());
       llvm::ConstantInt *AlignmentCI = cast<llvm::ConstantInt>(Alignment);
       EmitAlignmentAssumption(Ret.getScalarVal(), RetTy, Loc, AA->getLocation(),
-                              AlignmentCI->getZExtValue(), OffsetValue);
+                              AlignmentCI, OffsetValue);
     } else if (const auto *AA = TargetDecl->getAttr<AllocAlignAttr>()) {
       llvm::Value *AlignmentVal = CallArgs[AA->getParamIndex().getLLVMIndex()]
                                       .getRValue(*this)

diff --git a/lib/CodeGen/CGExprScalar.cpp b/lib/CodeGen/CGExprScalar.cpp
index 0b9271b1d31fc7ad21b8ed56884beb62d4ba24c2..c7f279d28e83168c488f3a45b504abfc154036f2 100644 (file)
--- a/lib/CodeGen/CGExprScalar.cpp
+++ b/lib/CodeGen/CGExprScalar.cpp
@@ -294,8 +294,7 @@ public:
 
     Value *AlignmentValue = CGF.EmitScalarExpr(AVAttr->getAlignment());
     llvm::ConstantInt *AlignmentCI = cast<llvm::ConstantInt>(AlignmentValue);
-    CGF.EmitAlignmentAssumption(V, E, AVAttr->getLocation(),
-                                AlignmentCI->getZExtValue());
+    CGF.EmitAlignmentAssumption(V, E, AVAttr->getLocation(), AlignmentCI);
   }
 
   /// EmitLoadOfLValue - Given an expression with complex type that represents a

diff --git a/lib/CodeGen/CGStmtOpenMP.cpp b/lib/CodeGen/CGStmtOpenMP.cpp
index e50cdb1b678f837a8e2441f5966a09ea72d0be56..fa4304d7e5ca2497ed71113f18be85a142d63490 100644 (file)
--- a/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/lib/CodeGen/CGStmtOpenMP.cpp
@@ -1519,14 +1519,14 @@ static void emitAlignedClause(CodeGenFunction &CGF,
   if (!CGF.HaveInsertPoint())
     return;
   for (const auto *Clause : D.getClausesOfKind<OMPAlignedClause>()) {
-    unsigned ClauseAlignment = 0;
+    size_t ClauseAlignment = 0;
     if (const Expr *AlignmentExpr = Clause->getAlignment()) {
       auto *AlignmentCI =
           cast<llvm::ConstantInt>(CGF.EmitScalarExpr(AlignmentExpr));
-      ClauseAlignment = static_cast<unsigned>(AlignmentCI->getZExtValue());
+      ClauseAlignment = AlignmentCI->getZExtValue();
     }
     for (const Expr *E : Clause->varlists()) {
-      unsigned Alignment = ClauseAlignment;
+      size_t Alignment = ClauseAlignment;
       if (Alignment == 0) {
         // OpenMP [2.8.1, Description]
         // If no optional parameter is specified, implementation-defined default
@@ -1542,7 +1542,8 @@ static void emitAlignedClause(CodeGenFunction &CGF,
       if (Alignment != 0) {
         llvm::Value *PtrValue = CGF.EmitScalarExpr(E);
         CGF.EmitAlignmentAssumption(
-            PtrValue, E, /*No second loc needed*/ SourceLocation(), Alignment);
+            PtrValue, E, /*No second loc needed*/ SourceLocation(),
+            llvm::ConstantInt::get(CGF.SizeTy, Alignment));
       }
     }
   }

diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 41b7f2f4b1be9153e030fec64875f01d413615ba..3f9a52ab7638aff79130ba7cd0f1277f70c2dd2f 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -2056,25 +2056,10 @@ void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
   }
 }
 
-void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
-                                              QualType Ty, SourceLocation Loc,
-                                              SourceLocation AssumptionLoc,
-                                              unsigned Alignment,
-                                              llvm::Value *OffsetValue) {
-  llvm::Value *TheCheck;
-  llvm::Instruction *Assumption = Builder.CreateAlignmentAssumption(
-      CGM.getDataLayout(), PtrValue, Alignment, OffsetValue, &TheCheck);
-  if (SanOpts.has(SanitizerKind::Alignment)) {
-    llvm::Value *AlignmentVal = llvm::ConstantInt::get(IntPtrTy, Alignment);
-    EmitAlignmentAssumptionCheck(PtrValue, Ty, Loc, AssumptionLoc, AlignmentVal,
-                                 OffsetValue, TheCheck, Assumption);
-  }
-}
-
 void CodeGenFunction::EmitAlignmentAssumption(llvm::Value *PtrValue,
                                               const Expr *E,
                                               SourceLocation AssumptionLoc,
-                                              unsigned Alignment,
+                                              llvm::Value *Alignment,
                                               llvm::Value *OffsetValue) {
   if (auto *CE = dyn_cast<CastExpr>(E))
     E = CE->getSubExprAsWritten();

diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index ea78309a06975d4e42becc53de57fd89cca9e185..bb4fed808373c7ac1f4139a08b70a47903d759a9 100644 (file)
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -2829,13 +2829,8 @@ public:
                                llvm::Value *Alignment,
                                llvm::Value *OffsetValue = nullptr);
 
-  void EmitAlignmentAssumption(llvm::Value *PtrValue, QualType Ty,
-                               SourceLocation Loc, SourceLocation AssumptionLoc,
-                               unsigned Alignment,
-                               llvm::Value *OffsetValue = nullptr);
-
   void EmitAlignmentAssumption(llvm::Value *PtrValue, const Expr *E,
-                               SourceLocation AssumptionLoc, unsigned Alignment,
+                               SourceLocation AssumptionLoc, llvm::Value *Alignment,
                                llvm::Value *OffsetValue = nullptr);
 
   //===--------------------------------------------------------------------===//

diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index 07d3648dc9ac8c78607766c75d1a500e8b954cb6..b35d591a7f285acc224baacfea9df27a6c8ae2ff 100644 (file)
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -6063,6 +6063,16 @@ bool Sema::SemaBuiltinAssumeAligned(CallExpr *TheCall) {
     if (!Result.isPowerOf2())
       return Diag(TheCall->getBeginLoc(), diag::err_alignment_not_power_of_two)
              << Arg->getSourceRange();
+
+    // FIXME: this should probably use llvm::Value::MaximumAlignment, however
+    // doing so results in a linking issue in GCC in a couple of assemblies.
+    // Alignment calculations can wrap around if it's greater than 2**28.
+    unsigned MaximumAlignment =
+        Context.getTargetInfo().getTriple().isOSBinFormatCOFF() ? 8192
+                                                                : 268435456;
+    if (Result > MaximumAlignment)
+      Diag(TheCall->getBeginLoc(), diag::warn_assume_aligned_too_great)
+          << Arg->getSourceRange() << MaximumAlignment;
   }
 
   if (NumArgs > 2) {

diff --git a/test/Sema/builtin-assume-aligned.c b/test/Sema/builtin-assume-aligned.c
index 057a500b321afa913531687344c301d9a4796606..a669ed172de8072f4ae2040c1d3ee7c62c977a0e 100644 (file)
--- a/test/Sema/builtin-assume-aligned.c
+++ b/test/Sema/builtin-assume-aligned.c
@@ -58,3 +58,7 @@ void *test_no_fn_proto() __attribute__((assume_aligned)); // expected-error {{'a
 void *test_no_fn_proto() __attribute__((assume_aligned())); // expected-error {{'assume_aligned' attribute takes at least 1 argument}}
 void *test_no_fn_proto() __attribute__((assume_aligned(32, 45, 37))); // expected-error {{'assume_aligned' attribute takes no more than 2 arguments}}
 
+int pr43638(int *a) {
+  a = __builtin_assume_aligned(a, 4294967296); // expected-warning {{requested alignment must be 268435456 bytes or smaller; assumption ignored}}
+return a[0];
+}