Reduce comment, further simplify test

Author: SLTozer

clang/lib/CodeGen/CGCall.cpp

@@ -6001,10 +6001,8 @@ RValue CodeGenFunction::EmitCall(const CGFunctionInfo &CallInfo,
     for (auto it = EHStack.find(CurrentCleanupScopeDepth); it != EHStack.end();
          ++it) {
       EHCleanupScope *Cleanup = dyn_cast<EHCleanupScope>(&*it);
-      // Fake uses can be safely emitted immediately prior to the tail call; we
-      // choose to emit the fake use before the call rather than after, to avoid
-      // forcing variable values from every call on the "stack" to be preserved
-      // simultaneously.
+      // Fake uses can be safely emitted immediately prior to the tail call, so
+      // we choose to emit them just before the call here.
       if (Cleanup && Cleanup->isFakeUse()) {
         CGBuilderTy::InsertPointGuard IPG(Builder);
         Builder.SetInsertPoint(CI);

clang/test/CodeGenCXX/fake-use-musttail.cpp

@@ -1,56 +1,27 @@
-// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 5
 // RUN: %clang_cc1 -emit-llvm -fextend-variable-liveness -o - %s | FileCheck %s
 
 /// Tests that when we have fake uses in a function ending in a musttail call,
 /// we emit the fake uses and their corresponding loads immediately prior to the
 /// tail call.
 
-extern "C" char *bar(int *, const char *, int *, const int *, unsigned long);
+extern "C" char *bar(int *);
 
 // CHECK-LABEL: define dso_local ptr @foo(
-// CHECK-SAME: ptr noundef [[E:%.*]], ptr noundef [[F:%.*]], ptr noundef [[G:%.*]], ptr noundef [[H:%.*]], i64 noundef [[I:%.*]]) #[[ATTR0:[0-9]+]] {
+// CHECK-SAME:    ptr noundef [[E:%.*]])
 // CHECK-NEXT:  [[ENTRY:.*:]]
 // CHECK-NEXT:    [[E_ADDR:%.*]] = alloca ptr, align 8
-// CHECK-NEXT:    [[F_ADDR:%.*]] = alloca ptr, align 8
-// CHECK-NEXT:    [[G_ADDR:%.*]] = alloca ptr, align 8
-// CHECK-NEXT:    [[H_ADDR:%.*]] = alloca ptr, align 8
-// CHECK-NEXT:    [[I_ADDR:%.*]] = alloca i64, align 8
 // CHECK-NEXT:    store ptr [[E]], ptr [[E_ADDR]], align 8
-// CHECK-NEXT:    store ptr [[F]], ptr [[F_ADDR]], align 8
-// CHECK-NEXT:    store ptr [[G]], ptr [[G_ADDR]], align 8
-// CHECK-NEXT:    store ptr [[H]], ptr [[H_ADDR]], align 8
-// CHECK-NEXT:    store i64 [[I]], ptr [[I_ADDR]], align 8
 // CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[E_ADDR]], align 8
-// CHECK-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[F_ADDR]], align 8
-// CHECK-NEXT:    [[TMP2:%.*]] = load ptr, ptr [[G_ADDR]], align 8
-// CHECK-NEXT:    [[TMP3:%.*]] = load ptr, ptr [[H_ADDR]], align 8
-// CHECK-NEXT:    [[TMP4:%.*]] = load i64, ptr [[I_ADDR]], align 8
-// CHECK-NEXT:    [[FAKE_USE:%.*]] = load i64, ptr [[I_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(i64 [[FAKE_USE]]) #[[ATTR3:[0-9]+]]
-// CHECK-NEXT:    [[FAKE_USE1:%.*]] = load ptr, ptr [[H_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE1]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE2:%.*]] = load ptr, ptr [[G_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE2]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE3:%.*]] = load ptr, ptr [[F_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE3]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE4:%.*]] = load ptr, ptr [[E_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE4]]) #[[ATTR3]]
-// CHECK-NEXT:    [[CALL:%.*]] = musttail call ptr @bar(ptr noundef [[TMP0]], ptr noundef [[TMP1]], ptr noundef [[TMP2]], ptr noundef [[TMP3]], i64 noundef [[TMP4]])
+// CHECK-NEXT:    [[FAKE_USE:%.*]] = load ptr, ptr [[E_ADDR]]
+// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE]])
+// CHECK-NEXT:    [[CALL:%.*]] = musttail call ptr @bar(ptr noundef [[TMP0]])
 // CHECK-NEXT:    ret ptr [[CALL]]
-// CHECK:       [[BB5:.*:]]
-// CHECK-NEXT:    [[FAKE_USE5:%.*]] = load i64, ptr [[I_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(i64 [[FAKE_USE5]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE6:%.*]] = load ptr, ptr [[H_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE6]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE7:%.*]] = load ptr, ptr [[G_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE7]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE8:%.*]] = load ptr, ptr [[F_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE8]]) #[[ATTR3]]
-// CHECK-NEXT:    [[FAKE_USE9:%.*]] = load ptr, ptr [[E_ADDR]], align 8
-// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE9]]) #[[ATTR3]]
+
+// CHECK:       [[BB1:.*:]]
+// CHECK-NEXT:    [[FAKE_USE1:%.*]] = load ptr, ptr [[E_ADDR]]
+// CHECK-NEXT:    notail call void (...) @llvm.fake.use(ptr [[FAKE_USE1]])
 // CHECK-NEXT:    ret ptr undef
 //
-extern "C" const char *foo(int *e, const char *f, int *g, const int *h,
-                        unsigned long i) {
-  [[clang::musttail]] return bar(e, f, g, h, i);
+extern "C" const char *foo(int *e) {
+  [[clang::musttail]] return bar(e);
 }