r343892 - Emit CK_NoOp casts in C mode, not just C++.
James Y Knight via cfe-commits
cfe-commits at lists.llvm.org
Fri Oct 5 14:53:52 PDT 2018
Author: jyknight
Date: Fri Oct 5 14:53:51 2018
New Revision: 343892
URL: http://llvm.org/viewvc/llvm-project?rev=343892&view=rev
Log:
Emit CK_NoOp casts in C mode, not just C++.
Previously, it had been using CK_BitCast even for casts that only
change const/restrict/volatile. Now it will use CK_Noop where
appropriate.
This is an alternate solution to r336746.
Differential Revision: https://reviews.llvm.org/D52918
Added:
cfe/trunk/test/Sema/c-casts.c
Modified:
cfe/trunk/lib/AST/ExprConstant.cpp
cfe/trunk/lib/Sema/SemaExpr.cpp
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=343892&r1=343891&r2=343892&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Fri Oct 5 14:53:51 2018
@@ -5864,11 +5864,7 @@ bool PointerExprEvaluator::VisitCastExpr
// permitted in constant expressions in C++11. Bitcasts from cv void* are
// also static_casts, but we disallow them as a resolution to DR1312.
if (!E->getType()->isVoidPointerType()) {
- // If we changed anything other than cvr-qualifiers, we can't use this
- // value for constant folding. FIXME: Qualification conversions should
- // always be CK_NoOp, but we get this wrong in C.
- if (!Info.Ctx.hasCvrSimilarType(E->getType(), E->getSubExpr()->getType()))
- Result.Designator.setInvalid();
+ Result.Designator.setInvalid();
if (SubExpr->getType()->isVoidPointerType())
CCEDiag(E, diag::note_constexpr_invalid_cast)
<< 3 << SubExpr->getType();
Modified: cfe/trunk/lib/Sema/SemaExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=343892&r1=343891&r2=343892&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaExpr.cpp (original)
+++ cfe/trunk/lib/Sema/SemaExpr.cpp Fri Oct 5 14:53:51 2018
@@ -5862,6 +5862,8 @@ CastKind Sema::PrepareScalarCast(ExprRes
LangAS DestAS = DestTy->getPointeeType().getAddressSpace();
if (SrcAS != DestAS)
return CK_AddressSpaceConversion;
+ if (Context.hasCvrSimilarType(SrcTy, DestTy))
+ return CK_NoOp;
return CK_BitCast;
}
case Type::STK_BlockPointer:
@@ -7762,7 +7764,12 @@ Sema::CheckAssignmentConstraints(QualTyp
if (isa<PointerType>(RHSType)) {
LangAS AddrSpaceL = LHSPointer->getPointeeType().getAddressSpace();
LangAS AddrSpaceR = RHSType->getPointeeType().getAddressSpace();
- Kind = AddrSpaceL != AddrSpaceR ? CK_AddressSpaceConversion : CK_BitCast;
+ if (AddrSpaceL != AddrSpaceR)
+ Kind = CK_AddressSpaceConversion;
+ else if (Context.hasCvrSimilarType(RHSType, LHSType))
+ Kind = CK_NoOp;
+ else
+ Kind = CK_BitCast;
return checkPointerTypesForAssignment(*this, LHSType, RHSType);
}
Added: cfe/trunk/test/Sema/c-casts.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/c-casts.c?rev=343892&view=auto
==============================================================================
--- cfe/trunk/test/Sema/c-casts.c (added)
+++ cfe/trunk/test/Sema/c-casts.c Fri Oct 5 14:53:51 2018
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -w -ast-dump %s | FileCheck %s
+
+// The cast construction code both for implicit and c-style casts is very
+// different in C vs C++. This file is intended to test the C behavior.
+
+// TODO: add tests covering the rest of the code in
+// Sema::CheckAssignmentConstraints and Sema::PrepareScalarCast
+
+// CHECK-LABEL: FunctionDecl {{.*}} cast_cvr_pointer
+void cast_cvr_pointer(char volatile * __restrict * const * p) {
+ char*** x;
+ // CHECK: ImplicitCastExpr {{.*}} 'char ***' <NoOp>
+ x = p;
+ // CHECK: CStyleCastExpr {{.*}} 'char ***' <NoOp>
+ x = (char***)p;
+}
+
+// CHECK-LABEL: FunctionDecl {{.*}} cast_pointer_type
+void cast_pointer_type(char *p) {
+ void *x;
+ // CHECK: ImplicitCastExpr {{.*}} 'void *' <BitCast>
+ x = p;
+ // CHECK: CStyleCastExpr {{.*}} 'void *' <BitCast>
+ x = (void*)p;
+}
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