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

[Timm Baeder via cfe-commits]

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

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

>From 2be9e0aa010451324cd3a1e873fb8640535823d7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Mon, 30 Sep 2024 11:39:57 +0200
Subject: [PATCH] [clang][bytecode] Remove superfluous check from fixed-point
 div

We shouldn't do this check for fixed-point values, at least the current
interpreter doesn't do it.
---
 clang/lib/AST/ByteCode/Interp.h             | 18 ++++++++++--------
 clang/test/Frontend/fixed_point_div_const.c |  3 +++
 2 files changed, 13 insertions(+), 8 deletions(-)

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