[clang] [clang][bytecode] Remove superfluous check from fixed-point div (PR #110478)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Timm Baeder (tbaederr)

<details>
<summary>Changes</summary>

We shouldn't do this check for fixed-point values, at least the current interpreter doesn't do it.

---
Full diff: https://github.com/llvm/llvm-project/pull/110478.diff


2 Files Affected:

- (modified) clang/lib/AST/ByteCode/Interp.h (+10-8) 
- (modified) clang/test/Frontend/fixed_point_div_const.c (+3) 


``````````diff
diff --git a/clang/lib/AST/ByteCode/Interp.h b/clang/lib/AST/ByteCode/Interp.h
index 68c04587a4919e..8a3c6810e0e11b 100644
--- a/clang/lib/AST/ByteCode/Interp.h
+++ b/clang/lib/AST/ByteCode/Interp.h
@@ -235,14 +235,16 @@ bool CheckDivRem(InterpState &S, CodePtr OpPC, const T &LHS, const T &RHS) {
     return false;
   }
 
-  if (LHS.isSigned() && LHS.isMin() && RHS.isNegative() && RHS.isMinusOne()) {
-    APSInt LHSInt = LHS.toAPSInt();
-    SmallString<32> Trunc;
-    (-LHSInt.extend(LHSInt.getBitWidth() + 1)).toString(Trunc, 10);
-    const SourceInfo &Loc = S.Current->getSource(OpPC);
-    const Expr *E = S.Current->getExpr(OpPC);
-    S.CCEDiag(Loc, diag::note_constexpr_overflow) << Trunc << E->getType();
-    return false;
+  if constexpr (!std::is_same_v<T, FixedPoint>) {
+    if (LHS.isSigned() && LHS.isMin() && RHS.isNegative() && RHS.isMinusOne()) {
+      APSInt LHSInt = LHS.toAPSInt();
+      SmallString<32> Trunc;
+      (-LHSInt.extend(LHSInt.getBitWidth() + 1)).toString(Trunc, 10);
+      const SourceInfo &Loc = S.Current->getSource(OpPC);
+      const Expr *E = S.Current->getExpr(OpPC);
+      S.CCEDiag(Loc, diag::note_constexpr_overflow) << Trunc << E->getType();
+      return false;
+    }
   }
   return true;
 }
diff --git a/clang/test/Frontend/fixed_point_div_const.c b/clang/test/Frontend/fixed_point_div_const.c
index 46935207d186a8..66c028e608db60 100644
--- a/clang/test/Frontend/fixed_point_div_const.c
+++ b/clang/test/Frontend/fixed_point_div_const.c
@@ -1,6 +1,9 @@
 // RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,SIGNED
 // RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -fpadding-on-unsigned-fixed-point -emit-llvm %s -o - | FileCheck %s --check-prefixes=CHECK,UNSIGNED
 
+// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - -fexperimental-new-constant-interpreter | FileCheck %s --check-prefixes=CHECK,SIGNED
+// RUN: %clang_cc1 -ffixed-point -triple x86_64-unknown-linux-gnu -fpadding-on-unsigned-fixed-point -emit-llvm %s -o - -fexperimental-new-constant-interpreter | FileCheck %s --check-prefixes=CHECK,UNSIGNED
+
 // Division between different fixed point types
 short _Accum sa_const = 1.0hk / 2.0hk;
 // CHECK-DAG: @sa_const  = {{.*}}global i16 64, align 2

``````````

</details>


https://github.com/llvm/llvm-project/pull/110478