[clang] [clang][Interp] Implement inc/dec for IntegralAP (PR #69597)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/69597

>From be120871fa8486ce9dd6cabb0a0b27d8371896b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Wed, 18 Oct 2023 15:36:13 +0200
Subject: [PATCH] [clang][Interp] Implement inc/dec for IntegralAP

---
 clang/lib/AST/Interp/IntegralAP.h | 12 ++---
 clang/test/AST/Interp/intap.cpp   | 81 ++++++++++++++++++++++++-------
 2 files changed, 68 insertions(+), 25 deletions(-)

diff --git a/clang/lib/AST/Interp/IntegralAP.h b/clang/lib/AST/Interp/IntegralAP.h
index 88de1f1392e6813..82da79a55b05312 100644
--- a/clang/lib/AST/Interp/IntegralAP.h
+++ b/clang/lib/AST/Interp/IntegralAP.h
@@ -177,17 +177,13 @@ template <bool Signed> class IntegralAP final {
   }
 
   static bool increment(IntegralAP A, IntegralAP *R) {
-    // FIXME: Implement.
-    assert(false);
-    *R = IntegralAP(A.V - 1);
-    return false;
+    IntegralAP<Signed> One(1, A.bitWidth());
+    return add(A, One, A.bitWidth() + 1, R);
   }
 
   static bool decrement(IntegralAP A, IntegralAP *R) {
-    // FIXME: Implement.
-    assert(false);
-    *R = IntegralAP(A.V - 1);
-    return false;
+    IntegralAP<Signed> One(1, A.bitWidth());
+    return sub(A, One, A.bitWidth() + 1, R);
   }
 
   static bool add(IntegralAP A, IntegralAP B, unsigned OpBits, IntegralAP *R) {
diff --git a/clang/test/AST/Interp/intap.cpp b/clang/test/AST/Interp/intap.cpp
index 34c8d0565082994..73c795732ff1055 100644
--- a/clang/test/AST/Interp/intap.cpp
+++ b/clang/test/AST/Interp/intap.cpp
@@ -43,9 +43,25 @@ namespace APCast {
 }
 
 #ifdef __SIZEOF_INT128__
+typedef __int128 int128_t;
+typedef unsigned __int128 uint128_t;
+static const __uint128_t UINT128_MAX =__uint128_t(__int128_t(-1L));
+static_assert(UINT128_MAX == -1, "");
+static_assert(UINT128_MAX == 1, ""); // expected-error {{static assertion failed}} \
+                                     // expected-note {{'340282366920938463463374607431768211455 == 1'}} \
+                                     // ref-error {{static assertion failed}} \
+                                     // ref-note {{'340282366920938463463374607431768211455 == 1'}}
+
+static const __int128_t INT128_MAX = UINT128_MAX >> (__int128_t)1;
+static_assert(INT128_MAX != 0, "");
+static_assert(INT128_MAX == 0, ""); // expected-error {{failed}} \
+                                    // expected-note {{evaluates to '170141183460469231731687303715884105727 == 0'}} \
+                                    // ref-error {{failed}} \
+                                    // ref-note {{evaluates to '170141183460469231731687303715884105727 == 0'}}
+static const __int128_t INT128_MIN = -INT128_MAX - 1;
+
 namespace i128 {
-  typedef __int128 int128_t;
-  typedef unsigned __int128 uint128_t;
+
   constexpr int128_t I128_1 = 12;
   static_assert(I128_1 == 12, "");
   static_assert(I128_1 != 10, "");
@@ -54,21 +70,6 @@ namespace i128 {
                                    // expected-note{{evaluates to}} \
                                    // ref-note{{evaluates to}}
 
-  static const __uint128_t UINT128_MAX =__uint128_t(__int128_t(-1L));
-  static_assert(UINT128_MAX == -1, "");
-  static_assert(UINT128_MAX == 1, ""); // expected-error {{static assertion failed}} \
-                                       // expected-note {{'340282366920938463463374607431768211455 == 1'}} \
-                                       // ref-error {{static assertion failed}} \
-                                       // ref-note {{'340282366920938463463374607431768211455 == 1'}}
-
-  static const __int128_t INT128_MAX = UINT128_MAX >> (__int128_t)1;
-  static_assert(INT128_MAX != 0, "");
-  static_assert(INT128_MAX == 0, ""); // expected-error {{failed}} \
-                                      // expected-note {{evaluates to '170141183460469231731687303715884105727 == 0'}} \
-                                      // ref-error {{failed}} \
-                                      // ref-note {{evaluates to '170141183460469231731687303715884105727 == 0'}}
-
-  static const __int128_t INT128_MIN = -INT128_MAX - 1;
   constexpr __int128 A = INT128_MAX + 1; // expected-error {{must be initialized by a constant expression}} \
                                          // expected-note {{value 170141183460469231731687303715884105728 is outside the range}} \
                                          // ref-error {{must be initialized by a constant expression}} \
@@ -157,4 +158,50 @@ namespace Bitfields {
                         // expected-warning {{changes value from 100 to 0}}
 }
 
+namespace IncDec {
+#if __cplusplus >= 201402L
+  constexpr int128_t maxPlus1(bool Pre) {
+    int128_t a = INT128_MAX;
+
+    if (Pre)
+      ++a; // ref-note {{value 170141183460469231731687303715884105728 is outside the range}} \
+           // expected-note {{value 170141183460469231731687303715884105728 is outside the range}}
+    else
+      a++; // ref-note {{value 170141183460469231731687303715884105728 is outside the range}} \
+           // expected-note {{value 170141183460469231731687303715884105728 is outside the range}}
+    return a;
+  }
+  static_assert(maxPlus1(true) == 0, ""); // ref-error {{not an integral constant expression}} \
+                                          // ref-note {{in call to}} \
+                                          // expected-error {{not an integral constant expression}} \
+                                          // expected-note {{in call to}}
+  static_assert(maxPlus1(false) == 0, ""); // ref-error {{not an integral constant expression}} \
+                                           // ref-note {{in call to}} \
+                                           // expected-error {{not an integral constant expression}} \
+                                           // expected-note {{in call to}}
+
+  constexpr int128_t inc1(bool Pre) {
+    int128_t A = 0;
+    if (Pre)
+      ++A;
+    else
+      A++;
+    return A;
+  }
+  static_assert(inc1(true) == 1, "");
+  static_assert(inc1(false) == 1, "");
+
+  constexpr int128_t dec1(bool Pre) {
+    int128_t A = 2;
+    if (Pre)
+      --A;
+    else
+      A--;
+    return A;
+  }
+  static_assert(dec1(true) == 1, "");
+  static_assert(dec1(false) == 1, "");
+#endif
+}
+
 #endif