From 5ae3211b105126d0db3bf07777edc8ecb1c8a3b0 Mon Sep 17 00:00:00 2001 From: Karl-Johan Karlsson Date: Sat, 26 Aug 2023 20:35:30 +0200 Subject: [PATCH] [builtins] Fix signed shift overflows in ashlti3.c, ashrti3.c, ashldi3.c and ashrdi3.c When compiling the builtins with the undefined behavior sanitizer and running testcases you end up with the following warning: UBSan: ashlti3.c:33:35: left shift of 1 by 63 places cannot be represented in type 'di_int' (aka 'long long') UBSan: ashrti3.c:34:34: left shift of negative value -81985529216486891 This can be avoided by doing the shift in a matching unsigned variant of the type. The same kind of patterns are found in ashldi3.c and ashrdi3.c This was found in an out of tree target. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D158819 --- compiler-rt/lib/builtins/ashldi3.c | 3 ++- compiler-rt/lib/builtins/ashlti3.c | 3 ++- compiler-rt/lib/builtins/ashrdi3.c | 3 ++- compiler-rt/lib/builtins/ashrti3.c | 3 ++- 4 files changed, 8 insertions(+), 4 deletions(-) diff --git a/compiler-rt/lib/builtins/ashldi3.c b/compiler-rt/lib/builtins/ashldi3.c index 04f22228f11d..7b835da865d7 100644 --- a/compiler-rt/lib/builtins/ashldi3.c +++ b/compiler-rt/lib/builtins/ashldi3.c @@ -28,7 +28,8 @@ COMPILER_RT_ABI di_int __ashldi3(di_int a, int b) { if (b == 0) return a; result.s.low = input.s.low << b; - result.s.high = (input.s.high << b) | (input.s.low >> (bits_in_word - b)); + result.s.high = + ((su_int)input.s.high << b) | (input.s.low >> (bits_in_word - b)); } return result.all; } diff --git a/compiler-rt/lib/builtins/ashlti3.c b/compiler-rt/lib/builtins/ashlti3.c index 99a133ffa22f..2bebf10401d3 100644 --- a/compiler-rt/lib/builtins/ashlti3.c +++ b/compiler-rt/lib/builtins/ashlti3.c @@ -30,7 +30,8 @@ COMPILER_RT_ABI ti_int __ashlti3(ti_int a, int b) { if (b == 0) return a; result.s.low = input.s.low << b; - result.s.high = (input.s.high << b) | (input.s.low >> (bits_in_dword - b)); + result.s.high = + ((du_int)input.s.high << b) | (input.s.low >> (bits_in_dword - b)); } return result.all; } diff --git a/compiler-rt/lib/builtins/ashrdi3.c b/compiler-rt/lib/builtins/ashrdi3.c index 934a5c47fd69..c0879b8b252d 100644 --- a/compiler-rt/lib/builtins/ashrdi3.c +++ b/compiler-rt/lib/builtins/ashrdi3.c @@ -29,7 +29,8 @@ COMPILER_RT_ABI di_int __ashrdi3(di_int a, int b) { if (b == 0) return a; result.s.high = input.s.high >> b; - result.s.low = (input.s.high << (bits_in_word - b)) | (input.s.low >> b); + result.s.low = + ((su_int)input.s.high << (bits_in_word - b)) | (input.s.low >> b); } return result.all; } diff --git a/compiler-rt/lib/builtins/ashrti3.c b/compiler-rt/lib/builtins/ashrti3.c index b306051df028..d6b1ad9192bf 100644 --- a/compiler-rt/lib/builtins/ashrti3.c +++ b/compiler-rt/lib/builtins/ashrti3.c @@ -31,7 +31,8 @@ COMPILER_RT_ABI ti_int __ashrti3(ti_int a, int b) { if (b == 0) return a; result.s.high = input.s.high >> b; - result.s.low = (input.s.high << (bits_in_dword - b)) | (input.s.low >> b); + result.s.low = + ((du_int)input.s.high << (bits_in_dword - b)) | (input.s.low >> b); } return result.all; }