[KeyInstr][Clang] Bitfield atom

[OCHyams]

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

[OCHyams]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [NFC][KeyInstr][Clang] Add some additional tests #134654
• [KeyInstr][Clang] Coerced store atoms #134653
• [KeyInstr][Clang] Ret atom #134652
• [KeyIntsr][Clang] Builtins alloca auto-init atom #134651
• [KeyInstr][Clang] Assign matrix element atom #134650
• [KeyInstr][Clang] Assign vector element atom #134649
• [KeyInstr][Clang] Bitfield atom #134648 👈 (View in Graphite)
• [KeyInstr][Clang] For range stmt atoms #134647
• [KeyInstr][Clang] For stmt atom #134646
• [KeyInstr][Clang] While stmt atom #134645
• [KeyInstr][Clang] Do stmt atom #134644
• [KeyInstr][Clang] Switch stmt atom #134643
• [KeyInstr][Clang] If stmt atom #134642
• [KeyInstr][Clang] Catch variable init atom #134641
• [KeyInstr][Clang] Member initalization atom #134640
• [KeyInstr][Clang] Aggregate init + copy #134639
• [KeyInstr] Complex assignment atoms #134638
• [KeyInstr][Clang] Assignment atom group #134637
• [KeyInstr][Clang] Static variable init atom #134636
• [KeyInstr][Clang] Agg init atom #134635
• [Clang][NFC] Move some static functions into CodeGenFunction #134634
• [KeyInstr][Clang] Scalar init atom #134633
• [KeyInstr][Clang] Add ApplyAtomGroup #134632
• [KeyInstr][Clang] Add Clang option -g[no-]key-instructions #134627
• [KeyInstr][DwarfDebug] Add is_stmt emission support #133495
• [KeyInstr] Add MIR parser support #133494
• [KeyInstr] Remap cloned PHIs in BreakCriticalEdges #133493
• Propagate DebugLocs on phis in BreakCriticalEdges #133492
• [KeyInstr][LoopUnswitch] Remap cloned instructions' atoms #133491
• [KeyInstr][LoopRotate] Remap atoms of duplicated instructions #133490
• [KeyInstr][LoopUnroll] Remap atoms while unrolling #133489
• [KeyInstr][JumpThreading] Remap atoms duping bb with cond br on phi into pred #133488
• [KeyInstr][JumpThreading] Remap atoms after threading #133487
• [KeyInstr][JumpThreading] Remap atoms in blocks duplicated for threading #133486
• [KeyInstr][Inline] Don't propagate atoms to inlined nodebug instructions #133485
• [KeyInstr][SimplifyCFG] Remap atoms after duplication for threading #133484
• [KeyInstr][debugify] Add --debugify-atoms to add key instructions metadata #133483
• [KeyInstr][SimplifyCFG] Remap atoms when folding br to common succ into pred #133482
• [KeyInstr] Inline atom info #133481
• [KeyInstr] Merge atoms in DILocation::getMergedLocation #133480
• [NFC][KeyInstr] Add Atom Group (re)mapping #133479
• [KeyInstr] Add Atom Group waterline to LLVMContext #133478
• [KeyInstr] Add fields to DILocation behind compile time flag #133477
• main

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[llvmbot]

@llvm/pr-subscribers-clang-codegen

@llvm/pr-subscribers-clang

Author: Orlando Cazalet-Hyams (OCHyams)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/134648.diff

2 Files Affected:

• (modified) clang/lib/CodeGen/CGExpr.cpp (+2-1)
• (added) clang/test/KeyInstructions/bitfield.cpp (+13)

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index 7408c498b3a1a..a5e113a1a4397 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -2614,7 +2614,8 @@ void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
   }
 
   // Write the new value back out.
-  Builder.CreateStore(SrcVal, Ptr, Dst.isVolatileQualified());
+  auto *I = Builder.CreateStore(SrcVal, Ptr, Dst.isVolatileQualified());
+  addInstToCurrentSourceAtom(I, SrcVal);
 
   // Return the new value of the bit-field, if requested.
   if (Result) {
diff --git a/clang/test/KeyInstructions/bitfield.cpp b/clang/test/KeyInstructions/bitfield.cpp
new file mode 100644
index 0000000000000..0586050ba8397
--- /dev/null
+++ b/clang/test/KeyInstructions/bitfield.cpp
@@ -0,0 +1,13 @@
+// RUN: %clang -gkey-instructions %s -gmlt -gcolumn-info -S -emit-llvm -o - \
+// RUN: | FileCheck %s --implicit-check-not atomGroup --implicit-check-not atomRank
+
+struct S { int a:3; };
+
+void foo(int x, S s) {
+// CHECK: %bf.set = or i8 %bf.clear, %bf.value, !dbg [[G1R2:!.*]]
+// CHECK: store i8 %bf.set, ptr %s, align 4, !dbg [[G1R1:!.*]]
+  s.a = x;
+}
+
+// CHECK: [[G1R2]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 2)
+// CHECK: [[G1R1]] = !DILocation({{.*}}, atomGroup: 1, atomRank: 1)

[SLTozer]

Maybe a small comment to the effect of, "Test for storing to a bitfield member, as this has distinct codegen to other variable/member stores"? Entirely optional since this may already be contextually obvious.