https://llvm.org/bugs/show_bug.cgi?id=23635
Bug ID: 23635
Summary: Instcombine wrongly preserves mul nsw
Product: libraries
Version: trunk
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Scalar Optimizations
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Classification: Unclassified
$ cat a.ll
define i2 @func34669005(i2, i1, i4, i2, i1, i4, i2, i1, i4, i2, i1, i4) {
%13 = mul nsw i2 %0, %3
%14 = mul nsw i2 %6, %0
%15 = sub nuw nsw i2 %13, %14
ret i2 %15
}
$ opt.exe -instcombine -S a.ll
define i2 @func34669005(i2, i1, i4, i2, i1, i4, i2, i1, i4, i2, i1, i4) {
%13 = sub i2 %3, %6
%14 = mul nsw i2 %13, %0
ret i2 %14
}
$ ./alive.py a.opt
----------------------------------------
%13 = mul nsw i2 %0, %3
%14 = mul nsw i2 %6, %0
%15 = sub nuw nsw i2 %13, %14
ret i2 %15
=>
%p13 = sub i2 %3, %6
%p14 = mul nsw i2 %p13, %0
ret i2 %p14
ERROR: Domain of poisoness of Target is smaller than Source's for i2 ret_
Example:
%0 i2 = 0x3 (3, -1)
%3 i2 = 0x1 (1)
%6 i2 = 0x3 (3, -1)
%13 i2 = 0x3 (3, -1)
%14 i2 = 0x1 (1)
%15 i2 = 0x2 (2, -2)
%p13 i2 = 0x2 (2, -2)
%p14 i2 = 0x2 (2, -2)
Source value: 0x2 (2, -2)
Target value: poison
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