Reland "[CodeGen] Fix crash when a function taking transparent union is redeclared."

When a function taking transparent union is declared as taking one of
union members earlier in the translation unit, clang would hit an
"Invalid cast" assertion during EmitFunctionProlog. This case
corresponds to function f1 in test/CodeGen/transparent-union-redecl.c.
We decided to cast i32 to union because after merging function
declarations function parameter type becomes int,
CGFunctionInfo::ArgInfo type matches with ABIArgInfo type, so we decide
it is a trivial case. But these types should also be castable to
parameter declaration type which is not the case here.

Now the fix is in converting from ABIArgInfo type to VarDecl type and using
argument demotion when necessary.

Additional tests in Sema/transparent-union.c capture current behavior and make
sure there are no regressions.

rdar://problem/34949329

Reviewers: rjmccall, rafael

Reviewed By: rjmccall

Subscribers: aemerson, cfe-commits, kristof.beyls, ahatanak

Differential Revision: https://reviews.llvm.org/D41311

llvm-svn: 323156

clang/lib/CodeGen/CGCall.cpp

@@ -2251,11 +2251,16 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
   for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
        i != e; ++i, ++info_it, ++ArgNo) {
     const VarDecl *Arg = *i;
-    QualType Ty = info_it->type;
     const ABIArgInfo &ArgI = info_it->info;
 
     bool isPromoted =
       isa<ParmVarDecl>(Arg) && cast<ParmVarDecl>(Arg)->isKNRPromoted();
+    // We are converting from ABIArgInfo type to VarDecl type directly, unless
+    // the parameter is promoted. In this case we convert to
+    // CGFunctionInfo::ArgInfo type with subsequent argument demotion.
+    QualType Ty = isPromoted ? info_it->type : Arg->getType();
+    assert(hasScalarEvaluationKind(Ty) ==
+           hasScalarEvaluationKind(Arg->getType()));
 
     unsigned FirstIRArg, NumIRArgs;
     std::tie(FirstIRArg, NumIRArgs) = IRFunctionArgs.getIRArgs(ArgNo);

clang/test/CodeGen/kr-func-promote.c

@@ -1,6 +1,12 @@
 // RUN: %clang_cc1 -triple i386-unknown-unknown %s -emit-llvm -o - | FileCheck %s
-// CHECK: i32 @a(i32)
 
+// CHECK: i32 @a(i32
 int a();
 int a(x) short x; {return x;}
 
+// CHECK: void @b(double
+// CHECK: %[[ADDR:.*]] = alloca float, align 4
+// CHECK: %[[TRUNC:.*]] = fptrunc double %0 to float
+// CHECK: store float %[[TRUNC]], float* %[[ADDR]], align 4
+void b();
+void b(f) float f; {}

clang/test/CodeGen/transparent-union-redecl.c

@@ -0,0 +1,44 @@
+// RUN: %clang_cc1 -Werror -triple i386-linux -emit-llvm -o - %s | FileCheck %s
+
+// Test that different order of declarations is acceptable and that
+// implementing different redeclarations is acceptable.
+// rdar://problem/34949329
+
+typedef union {
+  int i;
+  float f;
+} TU __attribute__((transparent_union));
+
+// CHECK-LABEL: define void @f0(i32 %tu.coerce)
+// CHECK: %tu = alloca %union.TU, align 4
+// CHECK: %coerce.dive = getelementptr inbounds %union.TU, %union.TU* %tu, i32 0, i32 0
+// CHECK: store i32 %tu.coerce, i32* %coerce.dive, align 4
+void f0(TU tu) {}
+void f0(int i);
+
+// CHECK-LABEL: define void @f1(i32 %tu.coerce)
+// CHECK: %tu = alloca %union.TU, align 4
+// CHECK: %coerce.dive = getelementptr inbounds %union.TU, %union.TU* %tu, i32 0, i32 0
+// CHECK: store i32 %tu.coerce, i32* %coerce.dive, align 4
+void f1(int i);
+void f1(TU tu) {}
+
+// CHECK-LABEL: define void @f2(i32 %i)
+// CHECK: %i.addr = alloca i32, align 4
+// CHECK: store i32 %i, i32* %i.addr, align 4
+void f2(TU tu);
+void f2(int i) {}
+
+// CHECK-LABEL: define void @f3(i32 %i)
+// CHECK: %i.addr = alloca i32, align 4
+// CHECK: store i32 %i, i32* %i.addr, align 4
+void f3(int i) {}
+void f3(TU tu);
+
+// Also test functions with parameters specified K&R style.
+// CHECK-LABEL: define void @knrStyle(i32 %tu.coerce)
+// CHECK: %tu = alloca %union.TU, align 4
+// CHECK: %coerce.dive = getelementptr inbounds %union.TU, %union.TU* %tu, i32 0, i32 0
+// CHECK: store i32 %tu.coerce, i32* %coerce.dive, align 4
+void knrStyle(int i);
+void knrStyle(tu) TU tu; {}

clang/test/CodeGenCXX/microsoft-abi-multiple-nonvirtual-inheritance.cpp

@@ -88,8 +88,11 @@ void ChildOverride::right() {
 // ChildOverride::right gets 'this' cast to Right* in ECX (i.e. this+4) so we
 // need to adjust 'this' before use.
 //
+// CHECK: %[[THIS_STORE:.*]] = alloca %struct.ChildOverride*, align 4
 // CHECK: %[[THIS_ADDR:.*]] = alloca %struct.ChildOverride*, align 4
-// CHECK: %[[THIS_INIT:.*]] = bitcast i8* %[[ECX:.*]] to %struct.ChildOverride*
+// CHECK: %[[COERCE_VAL:.*]] = bitcast i8* %[[ECX:.*]] to %struct.ChildOverride*
+// CHECK: store %struct.ChildOverride* %[[COERCE_VAL]], %struct.ChildOverride** %[[THIS_STORE]], align 4
+// CHECK: %[[THIS_INIT:.*]] = load %struct.ChildOverride*, %struct.ChildOverride** %[[THIS_STORE]], align 4
 // CHECK: store %struct.ChildOverride* %[[THIS_INIT]], %struct.ChildOverride** %[[THIS_ADDR]], align 4
 // CHECK: %[[THIS_RELOAD:.*]] = load %struct.ChildOverride*, %struct.ChildOverride** %[[THIS_ADDR]]
 // CHECK: %[[THIS_i8:.*]] = bitcast %struct.ChildOverride* %[[THIS_RELOAD]] to i8*
@@ -132,8 +135,11 @@ struct GrandchildOverride : ChildOverride {
 void GrandchildOverride::right() {
 // CHECK-LABEL: define x86_thiscallcc void @"\01?right@GrandchildOverride@@UAEXXZ"(i8*
 //
+// CHECK: %[[THIS_STORE:.*]] = alloca %struct.GrandchildOverride*, align 4
 // CHECK: %[[THIS_ADDR:.*]] = alloca %struct.GrandchildOverride*, align 4
-// CHECK: %[[THIS_INIT:.*]] = bitcast i8* %[[ECX:.*]] to %struct.GrandchildOverride*
+// CHECK: %[[COERCE_VAL:.*]] = bitcast i8* %[[ECX:.*]] to %struct.GrandchildOverride*
+// CHECK: store %struct.GrandchildOverride* %[[COERCE_VAL]], %struct.GrandchildOverride** %[[THIS_STORE]], align 4
+// CHECK: %[[THIS_INIT:.*]] = load %struct.GrandchildOverride*, %struct.GrandchildOverride** %[[THIS_STORE]], align 4
 // CHECK: store %struct.GrandchildOverride* %[[THIS_INIT]], %struct.GrandchildOverride** %[[THIS_ADDR]], align 4
 // CHECK: %[[THIS_RELOAD:.*]] = load %struct.GrandchildOverride*, %struct.GrandchildOverride** %[[THIS_ADDR]]
 // CHECK: %[[THIS_i8:.*]] = bitcast %struct.GrandchildOverride* %[[THIS_RELOAD]] to i8*

clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance-vtordisps.cpp

@@ -25,6 +25,7 @@ D::D() {}  // Forces vftable emission.
 
 // CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPM@A@AEXXZ"
 // Note that the vtordisp is applied before really adjusting to D*.
+// CHECK: %[[COERCE_LOAD:.*]] = load %struct.D*, %struct.D** %{{.*}}
 // CHECK: %[[ECX:.*]] = load %struct.D*, %struct.D** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -4
@@ -36,6 +37,7 @@ D::D() {}  // Forces vftable emission.
 // CHECK: ret void
 
 // CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@D@@$4PPPPPPPI@3AEXXZ"
+// CHECK: %[[COERCE_LOAD:.*]] = load %struct.D*, %struct.D** %{{.*}}
 // CHECK: %[[ECX:.*]] = load %struct.D*, %struct.D** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.D* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -8
@@ -64,7 +66,8 @@ struct G : virtual F, virtual E {
 
 G::G() {}  // Forces vftable emission.
 
-// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*)
+// CHECK-LABEL: define linkonce_odr x86_thiscallcc void @"\01?f@E@@$R4BA@M@PPPPPPPM@7AEXXZ"(i8*
+// CHECK: %[[COERCE_LOAD:.*]] = load %struct.E*, %struct.E** %{{.*}}
 // CHECK: %[[ECX:.*]] = load %struct.E*, %struct.E** %{{.*}}
 // CHECK: %[[ECX_i8:.*]] = bitcast %struct.E* %[[ECX]] to i8*
 // CHECK: %[[VTORDISP_PTR_i8:.*]] = getelementptr inbounds i8, i8* %[[ECX_i8]], i32 -4

clang/test/CodeGenCXX/microsoft-abi-virtual-inheritance.cpp

@@ -115,9 +115,15 @@ void B::foo() {
 // B::foo gets 'this' cast to VBase* in ECX (i.e. this+8) so we
 // need to adjust 'this' before use.
 //
-// Store initial this:
+// Coerce this to correct type:
+// CHECK:   %[[THIS_STORE:.*]] = alloca %struct.B*
 // CHECK:   %[[THIS_ADDR:.*]] = alloca %struct.B*
-// CHECK:   store %struct.B* %{{.*}}, %struct.B** %[[THIS_ADDR]], align 4
+// CHECK:   %[[COERCE_VAL:.*]] = bitcast i8* %{{.*}} to %struct.B*
+// CHECK:   store %struct.B* %[[COERCE_VAL]], %struct.B** %[[THIS_STORE]], align 4
+//
+// Store initial this:
+// CHECK:   %[[THIS_INIT:.*]] = load %struct.B*, %struct.B** %[[THIS_STORE]]
+// CHECK:   store %struct.B* %[[THIS_INIT]], %struct.B** %[[THIS_ADDR]], align 4
 //
 // Reload and adjust the this parameter:
 // CHECK:   %[[THIS_RELOAD:.*]] = load %struct.B*, %struct.B** %[[THIS_ADDR]]

clang/test/Sema/transparent-union.c

@@ -43,6 +43,35 @@ void fi(int i) {} // expected-error{{conflicting types}}
 void fvpp(TU); // expected-note{{previous declaration is here}}
 void fvpp(void **v) {} // expected-error{{conflicting types}}
 
+/* Test redeclaring a function taking a transparent_union arg more than twice.
+   Merging different declarations depends on their order, vary order too. */
+
+void f_triple0(TU tu) {}
+void f_triple0(int *); // expected-note{{previous declaration is here}}
+void f_triple0(float *f); // expected-error{{conflicting types}}
+
+void f_triple1(int *);
+void f_triple1(TU tu) {} // expected-note{{previous definition is here}}
+void f_triple1(float *f); // expected-error{{conflicting types}}
+
+void f_triple2(int *); // expected-note{{previous declaration is here}}
+void f_triple2(float *f); // expected-error{{conflicting types}}
+void f_triple2(TU tu) {}
+
+/* Test calling redeclared function taking a transparent_union arg. */
+
+void f_callee(TU);
+void f_callee(int *i) {} // expected-note{{passing argument to parameter 'i' here}}
+
+void caller(void) {
+  TU tu;
+  f_callee(tu); // expected-error{{passing 'TU' to parameter of incompatible type 'int *'}}
+
+  int *i;
+  f_callee(i);
+}
+
+
 /* FIXME: we'd like to just use an "int" here and align it differently
    from the normal "int", but if we do so we lose the alignment
    information from the typedef within the compiler. */