Author: Yingwei Zheng Date: 2025-05-09T19:23:48+08:00 New Revision: 61a8da9367dc7949f36916749f6038453ea4197f
URL: https://github.com/llvm/llvm-project/commit/61a8da9367dc7949f36916749f6038453ea4197f DIFF: https://github.com/llvm/llvm-project/commit/61a8da9367dc7949f36916749f6038453ea4197f.diff LOG: [Clang][CodeGen] Add workaround for old glibc `__PTR_ALIGN` macro (#137851) This patch adds a workaround for the old glibc `__PTR_ALIGN` macro: ``` ((sizeof(long int) < sizeof(void *) ? (base) : (char *)0) + (((pointer) - (sizeof(long int) < sizeof(void *) ? (base) : (char *)0) + (align_mask)) & ~(align_mask))); ``` Closes https://github.com/llvm/llvm-project/issues/137833. Added: clang/test/CodeGen/glibc_ptr_align.c Modified: clang/lib/AST/Expr.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp index a4483a285ed4f..8557c3b82ca39 100644 --- a/clang/lib/AST/Expr.cpp +++ b/clang/lib/AST/Expr.cpp @@ -2247,6 +2247,16 @@ bool BinaryOperator::isNullPointerArithmeticExtension(ASTContext &Ctx, return false; } + // Workaround for old glibc's __PTR_ALIGN macro + if (auto *Select = + dyn_cast<ConditionalOperator>(PExp->IgnoreParenNoopCasts(Ctx))) { + // If the condition can be constant evaluated, we check the selected arm. + bool EvalResult; + if (!Select->getCond()->EvaluateAsBooleanCondition(EvalResult, Ctx)) + return false; + PExp = EvalResult ? Select->getTrueExpr() : Select->getFalseExpr(); + } + // Check that the pointer is a nullptr. if (!PExp->IgnoreParenCasts() ->isNullPointerConstant(Ctx, Expr::NPC_ValueDependentIsNotNull)) diff --git a/clang/test/CodeGen/glibc_ptr_align.c b/clang/test/CodeGen/glibc_ptr_align.c new file mode 100644 index 0000000000000..0656d61eb0caa --- /dev/null +++ b/clang/test/CodeGen/glibc_ptr_align.c @@ -0,0 +1,62 @@ +// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5 +// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -O3 -o - -emit-llvm %s | FileCheck %s + +// Make sure that we do not set inbounds flag if the base pointer may be a constant null. + +// CHECK-LABEL: define dso_local ptr @glibc_ptr_align( +// CHECK-SAME: ptr noundef readnone captures(none) [[BASE:%.*]], ptr noundef [[POINTER:%.*]], i64 noundef [[ALIGN_MASK:%.*]]) local_unnamed_addr #[[ATTR0:[0-9]+]] { +// CHECK-NEXT: [[ENTRY:.*:]] +// CHECK-NEXT: [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[POINTER]] to i64 +// CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[ALIGN_MASK]], [[SUB_PTR_LHS_CAST]] +// CHECK-NEXT: [[NOT:%.*]] = xor i64 [[ALIGN_MASK]], -1 +// CHECK-NEXT: [[AND:%.*]] = and i64 [[ADD]], [[NOT]] +// CHECK-NEXT: [[TMP0:%.*]] = inttoptr i64 [[AND]] to ptr +// CHECK-NEXT: ret ptr [[TMP0]] +// +char *glibc_ptr_align(char *base, char *pointer, long align_mask) { + return (sizeof(long int) < sizeof(void *) ? (base) : (char *)0) + + (((pointer) - + (sizeof(long int) < sizeof(void *) ? (base) : (char *)0) + + (align_mask)) & + ~(align_mask)); +} + +// CHECK-LABEL: define dso_local ptr @glibc_ptr_align_commuted( +// CHECK-SAME: ptr noundef readnone captures(none) [[BASE:%.*]], ptr noundef [[POINTER:%.*]], i64 noundef [[ALIGN_MASK:%.*]]) local_unnamed_addr #[[ATTR0]] { +// CHECK-NEXT: [[ENTRY:.*:]] +// CHECK-NEXT: [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[POINTER]] to i64 +// CHECK-NEXT: [[ADD:%.*]] = add nsw i64 [[ALIGN_MASK]], [[SUB_PTR_LHS_CAST]] +// CHECK-NEXT: [[NOT:%.*]] = xor i64 [[ALIGN_MASK]], -1 +// CHECK-NEXT: [[AND:%.*]] = and i64 [[ADD]], [[NOT]] +// CHECK-NEXT: [[TMP0:%.*]] = inttoptr i64 [[AND]] to ptr +// CHECK-NEXT: ret ptr [[TMP0]] +// +char *glibc_ptr_align_commuted(char *base, char *pointer, long align_mask) { + return (sizeof(long int) >= sizeof(void *) ? (char *)0 : (base)) + + (((pointer) - + (sizeof(long int) >= sizeof(void *) ? (char *)0 : (base)) + + (align_mask)) & + ~(align_mask)); +} + +// CHECK-LABEL: define dso_local ptr @glibc_ptr_align_non_constexpr( +// CHECK-SAME: ptr noundef [[BASE:%.*]], ptr noundef [[POINTER:%.*]], i64 noundef [[ALIGN_MASK:%.*]], i32 noundef [[COND:%.*]]) local_unnamed_addr #[[ATTR0]] { +// CHECK-NEXT: [[ENTRY:.*:]] +// CHECK-NEXT: [[TOBOOL_NOT:%.*]] = icmp eq i32 [[COND]], 0 +// CHECK-NEXT: [[COND1:%.*]] = select i1 [[TOBOOL_NOT]], ptr null, ptr [[BASE]] +// CHECK-NEXT: [[SUB_PTR_LHS_CAST:%.*]] = ptrtoint ptr [[POINTER]] to i64 +// CHECK-NEXT: [[SUB_PTR_RHS_CAST:%.*]] = ptrtoint ptr [[COND1]] to i64 +// CHECK-NEXT: [[SUB_PTR_SUB:%.*]] = add i64 [[ALIGN_MASK]], [[SUB_PTR_LHS_CAST]] +// CHECK-NEXT: [[ADD:%.*]] = sub i64 [[SUB_PTR_SUB]], [[SUB_PTR_RHS_CAST]] +// CHECK-NEXT: [[NOT:%.*]] = xor i64 [[ALIGN_MASK]], -1 +// CHECK-NEXT: [[AND:%.*]] = and i64 [[ADD]], [[NOT]] +// CHECK-NEXT: [[ADD_PTR:%.*]] = getelementptr inbounds i8, ptr [[COND1]], i64 [[AND]] +// CHECK-NEXT: ret ptr [[ADD_PTR]] +// +char *glibc_ptr_align_non_constexpr(char *base, char *pointer, long align_mask, int cond) { + return (cond ? (base) : (char *)0) + + (((pointer) - + (cond ? (base) : (char *)0) + + (align_mask)) & + ~(align_mask)); +} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
