Author: Alex Voicu Date: 2023-08-01T21:55:36+01:00 New Revision: 51a014cb2d9c6f8303f9b11ffc035d69cbeb9e21
URL: https://github.com/llvm/llvm-project/commit/51a014cb2d9c6f8303f9b11ffc035d69cbeb9e21 DIFF: https://github.com/llvm/llvm-project/commit/51a014cb2d9c6f8303f9b11ffc035d69cbeb9e21.diff LOG: [Clang][CodeGen] `__builtin_alloca`s should care about address spaces `alloca` instructions always return pointers to the `alloca` address space. This composes poorly with most HLLs which are address space agnostic and thus have all pointers point to generic/default. Static `alloca`s were already handled on the AST level, however dynamic `alloca`s were not, which would lead to subtly incorrect IR. This patch addresses that by inserting an address space cast iff the `alloca` address space is different from the default / expected. Reviewed By: rjmccall, arsenm Differential Revision: https://reviews.llvm.org/D156539 Added: clang/test/CodeGen/dynamic-alloca-with-address-space.c Modified: clang/lib/CodeGen/CGBuiltin.cpp Removed: ################################################################################ diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp index 1f1323e2f92045..803895f64214d9 100644 --- a/clang/lib/CodeGen/CGBuiltin.cpp +++ b/clang/lib/CodeGen/CGBuiltin.cpp @@ -3517,6 +3517,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, return RValue::get(Result); } + // An alloca will always return a pointer to the alloca (stack) address + // space. This address space need not be the same as the AST / Language + // default (e.g. in C / C++ auto vars are in the generic address space). At + // the AST level this is handled within CreateTempAlloca et al., but for the + // builtin / dynamic alloca we have to handle it here. We use an explicit cast + // instead of passing an AS to CreateAlloca so as to not inhibit optimisation. case Builtin::BIalloca: case Builtin::BI_alloca: case Builtin::BI__builtin_alloca_uninitialized: @@ -3532,6 +3538,13 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, AI->setAlignment(SuitableAlignmentInBytes); if (BuiltinID != Builtin::BI__builtin_alloca_uninitialized) initializeAlloca(*this, AI, Size, SuitableAlignmentInBytes); + LangAS AAS = getASTAllocaAddressSpace(); + LangAS EAS = E->getType()->getPointeeType().getAddressSpace(); + if (AAS != EAS) { + llvm::Type *Ty = CGM.getTypes().ConvertType(E->getType()); + return RValue::get(getTargetHooks().performAddrSpaceCast(*this, AI, AAS, + EAS, Ty)); + } return RValue::get(AI); } @@ -3547,6 +3560,13 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, AI->setAlignment(AlignmentInBytes); if (BuiltinID != Builtin::BI__builtin_alloca_with_align_uninitialized) initializeAlloca(*this, AI, Size, AlignmentInBytes); + LangAS AAS = getASTAllocaAddressSpace(); + LangAS EAS = E->getType()->getPointeeType().getAddressSpace(); + if (AAS != EAS) { + llvm::Type *Ty = CGM.getTypes().ConvertType(E->getType()); + return RValue::get(getTargetHooks().performAddrSpaceCast(*this, AI, AAS, + EAS, Ty)); + } return RValue::get(AI); } diff --git a/clang/test/CodeGen/dynamic-alloca-with-address-space.c b/clang/test/CodeGen/dynamic-alloca-with-address-space.c new file mode 100644 index 00000000000000..0ef9039e68968e --- /dev/null +++ b/clang/test/CodeGen/dynamic-alloca-with-address-space.c @@ -0,0 +1,41 @@ +// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -emit-llvm %s -o - \ +// RUN: | FileCheck %s --check-prefix=CHECK +// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -DOCL12 -x cl -std=cl1.2 \ +// RUN: -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-CL12 +// RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -x cl -std=cl2.0 \ +// RUN: -emit-llvm %s -o - | FileCheck %s --check-prefix=CHECK-CL20 + +#if defined(OCL12) + #define CAST (char *)(unsigned long) +#else + #define CAST (char *) +#endif + +void allocas(unsigned long n) { + char *a = CAST __builtin_alloca(n); + char *uninitialized_a = CAST __builtin_alloca_uninitialized(n); + char *aligned_a = CAST __builtin_alloca_with_align(n, 8); + char *aligned_uninitialized_a = CAST __builtin_alloca_with_align_uninitialized(n, 8); +} + +// CHECK: @allocas( +// CHECK: store i64 %n, ptr %n.addr.ascast, align 8 +// CHECK: %0 = load i64, ptr %n.addr.ascast, align 8 +// CHECK: %1 = alloca i8, i64 %0, align 8, addrspace(5) +// CHECK: %2 = addrspacecast ptr addrspace(5) %1 to ptr +// CHECK: store ptr %2, ptr %a.ascast, align 8 +// CHECK: %3 = load i64, ptr %n.addr.ascast, align 8 +// CHECK: %4 = alloca i8, i64 %3, align 8, addrspace(5) +// CHECK: %5 = addrspacecast ptr addrspace(5) %4 to ptr +// CHECK: store ptr %5, ptr %uninitialized_a.ascast, align 8 +// CHECK: %6 = load i64, ptr %n.addr.ascast, align 8 +// CHECK: %7 = alloca i8, i64 %6, align 1, addrspace(5) +// CHECK: %8 = addrspacecast ptr addrspace(5) %7 to ptr +// CHECK: store ptr %8, ptr %aligned_a.ascast, align 8 +// CHECK: %9 = load i64, ptr %n.addr.ascast, align 8 +// CHECK: %10 = alloca i8, i64 %9, align 1, addrspace(5) +// CHECK: %11 = addrspacecast ptr addrspace(5) %10 to ptr +// CHECK: store ptr %11, ptr %aligned_uninitialized_a.ascast, align 8 +// CHECK: ret void +// CHECK-CL12-NOT: addrspacecast +// CHECK-CL20-NOT: addrspacecast _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits