llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang @llvm/pr-subscribers-clang-codegen Author: None (serge-sans-paille) <details> <summary>Changes</summary> It is an undefined behavior to pass null arguments as memcpy source or destination parameter, so generate the appropriate llvm.assume call to communicate this to the backend. Don't do it for builtin memcpy as they don't suffer the same behavior in case of null size. --- Full diff: https://github.com/llvm/llvm-project/pull/119704.diff 2 Files Affected: - (modified) clang/lib/CodeGen/CGBuiltin.cpp (+6) - (modified) clang/test/CodeGen/catch-undef-behavior.c (+4) ``````````diff diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp index 497a0b3952af8c..50cd8529120d36 100644 --- a/clang/lib/CodeGen/CGBuiltin.cpp +++ b/clang/lib/CodeGen/CGBuiltin.cpp @@ -4531,6 +4531,12 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID, Value *SizeVal = EmitScalarExpr(E->getArg(2)); EmitArgCheck(TCK_Store, Dest, E->getArg(0), 0); EmitArgCheck(TCK_Load, Src, E->getArg(1), 1); + if (BuiltinID == Builtin::BImemcpy || BuiltinID == Builtin::BImempcpy) { + Builder.CreateAssumption( + Builder.CreateIsNotNull(Dest.emitRawPointer(*this))); + Builder.CreateAssumption( + Builder.CreateIsNotNull(Src.emitRawPointer(*this))); + } Builder.CreateMemCpy(Dest, Src, SizeVal, false); if (BuiltinID == Builtin::BImempcpy || BuiltinID == Builtin::BI__builtin_mempcpy) diff --git a/clang/test/CodeGen/catch-undef-behavior.c b/clang/test/CodeGen/catch-undef-behavior.c index 7580290b0b0333..7ef7c78f1cebb7 100644 --- a/clang/test/CodeGen/catch-undef-behavior.c +++ b/clang/test/CodeGen/catch-undef-behavior.c @@ -371,6 +371,10 @@ void call_memcpy_nonnull(void *p, void *q, int sz) { // CHECK-TRAP: call void @llvm.ubsantrap(i8 16) // CHECK-COMMON-NOT: call + // CHECK-COMMON: %5 = icmp ne ptr %0, null + // CHECK-COMMON: call void @llvm.assume(i1 %5) + // CHECK-COMMON: %6 = icmp ne ptr %0, null + // CHECK-COMMON: call void @llvm.assume(i1 %6) // CHECK-COMMON: call void @llvm.memcpy.p0.p0.i64(ptr align 1 %0, ptr align 1 %1, i64 %conv, i1 false) memcpy(p, q, sz); } `````````` </details> https://github.com/llvm/llvm-project/pull/119704 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
