[PATCH] D90218: Fix PR47973: Addressing integer division edge case with INT_MIN

[Ayshe Kuran via Phabricator via llvm-commits]

akuran updated this revision to Diff 301222.
akuran added a comment.

Restart build


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D90218/new/

https://reviews.llvm.org/D90218

Files:
  compiler-rt/lib/builtins/int_div_impl.inc


Index: compiler-rt/lib/builtins/int_div_impl.inc
===================================================================
--- compiler-rt/lib/builtins/int_div_impl.inc
+++ compiler-rt/lib/builtins/int_div_impl.inc
@@ -72,24 +72,24 @@
 #ifdef COMPUTE_UDIV
 static __inline fixint_t __divXi3(fixint_t a, fixint_t b) {
   const int N = (int)(sizeof(fixint_t) * CHAR_BIT) - 1;
-  fixint_t s_a = a >> N;                   // s_a = a < 0 ? -1 : 0
-  fixint_t s_b = b >> N;                   // s_b = b < 0 ? -1 : 0
-  a = (a ^ s_a) - s_a;                     // negate if s_a == -1
-  b = (b ^ s_b) - s_b;                     // negate if s_b == -1
-  s_a ^= s_b;                              // sign of quotient
-  return (COMPUTE_UDIV(a, b) ^ s_a) - s_a; // negate if s_a == -1
+  fixint_t s_a = a >> N;                            // s_a = a < 0 ? -1 : 0
+  fixint_t s_b = b >> N;                            // s_b = b < 0 ? -1 : 0
+  fixuint_t a_u = (fixuint_t)(a ^ s_a) + (-s_a);    // negate if s_a == -1
+  fixuint_t b_u = (fixuint_t)(b ^ s_b) + (-s_b);    // negate if s_b == -1
+  s_a ^= s_b;                                       // sign of quotient
+  return (COMPUTE_UDIV(a_u, b_u) ^ s_a) + (-s_a);   // negate if s_a == -1
 }
 #endif // COMPUTE_UDIV
 
 #ifdef ASSIGN_UMOD
 static __inline fixint_t __modXi3(fixint_t a, fixint_t b) {
   const int N = (int)(sizeof(fixint_t) * CHAR_BIT) - 1;
-  fixint_t s = b >> N;    // s = b < 0 ? -1 : 0
-  b = (b ^ s) - s;        // negate if s == -1
-  s = a >> N;             // s = a < 0 ? -1 : 0
-  a = (a ^ s) - s;        // negate if s == -1
+  fixint_t s = b >> N;                              // s = b < 0 ? -1 : 0
+  fixuint_t b_u = (fixuint_t)(b ^ s) + (-s);        // negate if s == -1
+  s = a >> N;                                       // s = a < 0 ? -1 : 0
+  fixuint_t a_u = (fixuint_t)(a ^ s) + (-s);        // negate if s == -1
   fixuint_t res;
-  ASSIGN_UMOD(res, a, b);
-  return (res ^ s) - s;   // negate if s == -1
+  ASSIGN_UMOD(res, a_u, b_u);
+  return (res ^ s) + (-s);                          // negate if s == -1
 }
 #endif // ASSIGN_UMOD


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