[NFC][KeyInstr][Clang] Add some additional tests

This patch is part of a stack that teaches Clang to generate Key Instructions
metadata for C and C++.

The Key Instructions project is introduced, including a "quick summary" section
at the top which adds context for this PR, here:
https://discourse.llvm.org/t/rfc-improving-is-stmt-placement-for-better-interactive-debugging/82668

The feature is only functional in LLVM if LLVM is built with CMake flag
LLVM_EXPERIMENTAL_KEY_INSTRUCTIONs. Eventually that flag will be removed.

The Clang-side work is demoed here:
#130943

new.cpp: Check store of addr and value are both added to same atom
cast.c: Check we look through casts
multi-func.c Check the atom group number is reset between functions

Author: OCHyams

clang/test/KeyInstructions/cast.c

@@ -0,0 +1,19 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o -  \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o -  \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+float g;
+void a() {
+// CHECK: %0 = load float, ptr @g{{.*}}, !dbg [[G1R3:!.*]]
+// CHECK: %conv = fptosi float %0 to i32{{.*}}, !dbg [[G1R2:!.*]]
+// CHECK: store i32 %conv, ptr %a{{.*}}, !dbg [[G1R1:!.*]]
+    int a = g;
+// CHECK: ret{{.*}}, !dbg [[G2R1:!.*]]
+}
+
+// CHECK: [[G1R3]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 3)
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G2R1]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)

clang/test/KeyInstructions/multi-func.c

@@ -0,0 +1,18 @@
+// RUN: %clang -gkey-instructions -gno-column-info -x c++ %s -gmlt -S -emit-llvm -o -  \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// RUN: %clang -gkey-instructions -gno-column-info -x c %s -gmlt -S -emit-llvm -o -  \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// Check atomGroup is reset to start at 1 in each function.
+
+// CHECK: ret{{.*}}, !dbg [[AG:!.*]]
+void a() {}
+
+// CHECK: ret{{.*}}, !dbg [[BG:!.*]]
+void b() {}
+
+// CHECK: [[A:!.*]] = distinct !DISubprogram(name: "a",
+// CHECK: [[AG]] = !DILocation({{.*}}, scope: [[A]], atomGroup: 1, atomRank: 1)
+// CHECK: [[B:!.*]] = distinct !DISubprogram(name: "b",
+// CHECK: [[BG]] = !DILocation({{.*}}, scope: [[B]], atomGroup: 1, atomRank: 1)

clang/test/KeyInstructions/new.cpp

@@ -0,0 +1,37 @@
+// RUN: %clang -gkey-instructions %s -gmlt -gcolumn-info -S -emit-llvm -o - -Wno-unused-variable \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+// Check both the addr-store and value-store are part of the same atom.
+
+void f(int x) {
+// CHECK: %call = call noalias noundef nonnull ptr @_Znwm{{.*}}, !dbg [[G1R2_C12:!.*]]
+// CHECK: %0 = load i32, ptr %x.addr{{.*}}, !dbg [[G1R2_C20:!.*]]
+// CHECK: store i32 %0, ptr %call{{.*}}, !dbg [[G1R1_C12:!.*]]
+// CHECK: store ptr %call, ptr %{{.*}}, !dbg [[G1R1_C8:!.*]]
+  int *n = new int(x);
+// CHECK: %call1 = call noalias noundef nonnull ptr @_Znwm{{.*}}, !dbg [[G2R2_C7:!.*]]
+// CHECK: %1 = load i32, ptr %x.addr{{.*}}, !dbg [[G2R2_C15:!.*]]
+// CHECK: store i32 %1, ptr %call{{.*}}, !dbg [[G2R1_C7:!.*]]
+// CHECK: store ptr %call1, ptr %{{.*}}, !dbg [[G2R1_C5:!.*]]
+  n = new int(x);
+// CHECK: %2 = load i32, ptr %x.addr{{.*}}, !dbg [[G3R2:!.*]]
+// CHECK: %3 = load ptr, ptr %n
+// CHECK: store i32 %2, ptr %3{{.*}}, !dbg [[G3R1:!.*]]
+  *n = x;
+// CHECK: ret void, !dbg [[G4R1:!.*]]
+}
+
+// CHECK: [[G1R2_C12]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R2_C20]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1_C12]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+// CHECK: [[G1R1_C8]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)
+
+// CHECK: [[G2R2_C7]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
+// CHECK: [[G2R2_C15]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 2)
+// CHECK: [[G2R1_C7]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+// CHECK: [[G2R1_C5]] = !DILocation({{.*}}, atomGroup: 2, atomRank: 1)
+
+// CHECK: [[G3R2]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 2)
+// CHECK: [[G3R1]] = !DILocation({{.*}}, atomGroup: 3, atomRank: 1)
+
+// CHECK: [[G4R1]] = !DILocation({{.*}}, atomGroup: 4, atomRank: 1)