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[clang] Generate appropriate assume in presence of libc's memcpy #119704

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[clang] Generate appropriate assume in presence of libc's memcpy #119704

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9d013f3
[clang] Generate appropriate assume in presence of libc's memcpy
serge-sans-paille Dec 12, 2024
55f33c4
fixup! [clang] Generate appropriate assume in presence of libc's memcpy
serge-sans-paille Dec 13, 2024
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7 changes: 7 additions & 0 deletions clang/lib/CodeGen/CGBuiltin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4531,6 +4531,13 @@ 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) {
Value *NullSize = Builder.CreateIsNull(SizeVal);
Builder.CreateAssumption(Builder.CreateOr(
NullSize, Builder.CreateIsNotNull(Dest.emitRawPointer(*this))));
Builder.CreateAssumption(Builder.CreateOr(
NullSize, Builder.CreateIsNotNull(Src.emitRawPointer(*this))));
}
Builder.CreateMemCpy(Dest, Src, SizeVal, false);
if (BuiltinID == Builtin::BImempcpy ||
BuiltinID == Builtin::BI__builtin_mempcpy)
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12 changes: 9 additions & 3 deletions clang/test/CodeGen/catch-undef-behavior.c
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Expand Up @@ -366,11 +366,17 @@ void call_memcpy_nonnull(void *p, void *q, int sz) {
// CHECK-TRAP: call void @llvm.ubsantrap(i8 16)
// CHECK-COMMON-NOT: call

// CHECK-COMMON: icmp ne ptr {{.*}}, null
// CHECK-COMMON: icmp ne ptr %[[#]], null
// CHECK-UBSAN: call void @__ubsan_handle_nonnull_arg
// CHECK-TRAP: call void @llvm.ubsantrap(i8 16)
// CHECK-COMMON-NOT: call

//
// CHECK-COMMON: icmp eq i64 %conv, 0
// CHECK-COMMON: icmp ne ptr %0, null
// CHECK-COMMON: or i1 %[[#]], %[[#]]
// CHECK-COMMON: call void @llvm.assume(i1 %[[#]])
// CHECK-COMMON: icmp ne ptr %1, null
// CHECK-COMMON: or i1 %[[#]], %[[#]]
// CHECK-COMMON: call void @llvm.assume(i1 %[[#]])
// 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);
}
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