ubsan: Pass floating-point arguments to the runtime by value if they fit the

value argument. If not, be sure we don't accidentally use a dynamic alloca.

llvm-svn: 177690

2 files changed, 36 insertions, 2 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index ad69ebe05f7..9bfaacbbd6a 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2078,6 +2078,15 @@ llvm::Constant *CodeGenFunction::EmitCheckTypeDescriptor(QualType T) {
 llvm::Value *CodeGenFunction::EmitCheckValue(llvm::Value *V) {
   llvm::Type *TargetTy = IntPtrTy;
 
+  // Floating-point types which fit into intptr_t are bitcast to integers
+  // and then passed directly (after zero-extension, if necessary).
+  if (V->getType()->isFloatingPointTy()) {
+    unsigned Bits = V->getType()->getPrimitiveSizeInBits();
+    if (Bits <= TargetTy->getIntegerBitWidth())
+      V = Builder.CreateBitCast(V, llvm::Type::getIntNTy(getLLVMContext(),
+                                                         Bits));
+  }
+
   // Integers which fit in intptr_t are zero-extended and passed directly.
   if (V->getType()->isIntegerTy() &&
       V->getType()->getIntegerBitWidth() <= TargetTy->getIntegerBitWidth())
@@ -2085,7 +2094,7 @@ llvm::Value *CodeGenFunction::EmitCheckValue(llvm::Value *V) {
 
   // Pointers are passed directly, everything else is passed by address.
   if (!V->getType()->isPointerTy()) {
-    llvm::Value *Ptr = Builder.CreateAlloca(V->getType());
+    llvm::Value *Ptr = CreateTempAlloca(V->getType());
     Builder.CreateStore(V, Ptr);
     V = Ptr;
   }
diff --git a/clang/test/CodeGen/catch-undef-behavior.c b/clang/test/CodeGen/catch-undef-behavior.c
index bd4973c069c..8e3388ea63e 100644
--- a/clang/test/CodeGen/catch-undef-behavior.c
+++ b/clang/test/CodeGen/catch-undef-behavior.c
@@ -288,7 +288,10 @@ int float_int_overflow(float f) {
   // CHECK: %[[GE:.*]] = fcmp ogt float %[[F:.*]], 0xC1E0000020000000
   // CHECK: %[[LE:.*]] = fcmp olt float %[[F]], 0x41E0000000000000
   // CHECK: and i1 %[[GE]], %[[LE]]
-  // CHECK: call void @__ubsan_handle_float_cast_overflow(
+
+  // CHECK: %[[CAST:.*]] = bitcast float %[[F]] to i32
+  // CHECK: %[[ARG:.*]] = zext i32 %[[CAST]] to i64
+  // CHECK: call void @__ubsan_handle_float_cast_overflow({{.*}}, i64 %[[ARG]]
 
   // CHECK-TRAP: %[[GE:.*]] = fcmp ogt float %[[F:.*]], 0xC1E0000020000000
   // CHECK-TRAP: %[[LE:.*]] = fcmp olt float %[[F]], 0x41E0000000000000
@@ -300,6 +303,28 @@ int float_int_overflow(float f) {
   return f;
 }
 
+// CHECK: @long_double_int_overflow
+// CHECK-TRAP: @long_double_int_overflow
+int long_double_int_overflow(long double ld) {
+  // CHECK: alloca x86_fp80
+  // CHECK: %[[GE:.*]] = fcmp ogt x86_fp80 %[[F:.*]], 0xKC01E8000000100000000
+  // CHECK: %[[LE:.*]] = fcmp olt x86_fp80 %[[F]], 0xK401E8000000000000000
+  // CHECK: and i1 %[[GE]], %[[LE]]
+
+  // CHECK: store x86_fp80 %[[F]], x86_fp80* %[[ALLOCA:.*]]
+  // CHECK: %[[ARG:.*]] = ptrtoint x86_fp80* %[[ALLOCA]] to i64
+  // CHECK: call void @__ubsan_handle_float_cast_overflow({{.*}}, i64 %[[ARG]]
+
+  // CHECK-TRAP: %[[GE:.*]] = fcmp ogt x86_fp80 %[[F:.*]], 0xKC01E800000010000000
+  // CHECK-TRAP: %[[LE:.*]] = fcmp olt x86_fp80 %[[F]], 0xK401E800000000000000
+  // CHECK-TRAP: %[[INBOUNDS:.*]] = and i1 %[[GE]], %[[LE]]
+  // CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]]
+
+  // CHECK-TRAP:      call void @llvm.trap() [[NR_NUW]]
+  // CHECK-TRAP-NEXT: unreachable
+  return ld;
+}
+
 // CHECK: @float_uint_overflow
 // CHECK-TRAP: @float_uint_overflow
 unsigned float_uint_overflow(float f) {