[clang] Add range metadata for atomic load of boolean type. #131476 (PR #133546)

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Jan =?utf-8?q?Górski?= <jan.a.gorski at wp.pl>,
Jan =?utf-8?q?Górski?= <jan.a.gorski at wp.pl>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/133546 at github.com>


llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Jan Górski (janagor)

<details>
<summary>Changes</summary>

Addresses #<!-- -->131476.

For `x86_64` it folds
```
movzbl	t1(%rip), %eax
andb	$1, %al
```
into
```
movzbl	t1(%rip), %eax
```
when run: `clang -S atomic-ops-load.c -o atomic-ops-load.s -O1 --target=x86_64`.

But for riscv replaces:
```
lb	a0, %lo(t1)(a0)
andi	a0, a0, 1
```
with
```
lb	a0, %lo(t1)(a0)
zext.b	a0, a0
``` 
when run: `when run `clang -S atomic-ops-load.c -o atomic-ops-load.s -O1 --target=riscv64`.

 

---
Full diff: https://github.com/llvm/llvm-project/pull/133546.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGAtomic.cpp (+23) 
- (added) clang/test/CodeGen/atomic-ops-load.c (+11) 


``````````diff
diff --git a/clang/lib/CodeGen/CGAtomic.cpp b/clang/lib/CodeGen/CGAtomic.cpp
index 3adb2a7ad207f..2c9613deef744 100644
--- a/clang/lib/CodeGen/CGAtomic.cpp
+++ b/clang/lib/CodeGen/CGAtomic.cpp
@@ -590,6 +590,29 @@ static void EmitAtomicOp(CodeGenFunction &CGF, AtomicExpr *E, Address Dest,
     llvm::LoadInst *Load = CGF.Builder.CreateLoad(Ptr);
     Load->setAtomic(Order, Scope);
     Load->setVolatile(E->isVolatile());
+
+    if (CGF.CGM.getCodeGenOpts().OptimizationLevel == 0) {
+      CGF.Builder.CreateStore(Load, Dest);
+      return;
+    }
+
+    QualType Ty = E->getValueType();
+    if (!Ty->isBooleanType()) {
+      CGF.Builder.CreateStore(Load, Dest);
+      return;
+    }
+
+    llvm::MDBuilder MDHelper(CGF.getLLVMContext());
+    llvm::APInt BooleanMin = llvm::APInt(CGF.getContext().getTypeSize(Ty), 0);
+    llvm::APInt BooleanEnd = llvm::APInt(CGF.getContext().getTypeSize(Ty), 2);
+
+    if (llvm::MDNode *RangeInfo =
+            MDHelper.createRange(BooleanMin, BooleanEnd)) {
+      Load->setMetadata(llvm::LLVMContext::MD_range, RangeInfo);
+      Load->setMetadata(llvm::LLVMContext::MD_noundef,
+                        llvm::MDNode::get(CGF.getLLVMContext(), {}));
+    }
+
     CGF.Builder.CreateStore(Load, Dest);
     return;
   }
diff --git a/clang/test/CodeGen/atomic-ops-load.c b/clang/test/CodeGen/atomic-ops-load.c
new file mode 100644
index 0000000000000..778a7ebdc2618
--- /dev/null
+++ b/clang/test/CodeGen/atomic-ops-load.c
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple riscv64 -O1 -emit-llvm %s -o - | FileCheck %s
+#include <stdbool.h>
+
+extern bool t1;
+bool test1(void) {
+// CHECK-LABEL: define{{.*}} i1 @test1
+// CHECK: load atomic i8, ptr @t1 monotonic, align 1, !range ![[$WS_RANGE:[0-9]*]], !noundef !{{[0-9]+}}
+// CHECK-NEXT: trunc nuw i8 %{{.*}} to i1
+// CHECK-NEXT: ret i1 %{{.*}}
+  return __atomic_load_n(&t1, __ATOMIC_RELAXED);
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/133546