| Issue |
115123
|
| Summary |
[CorrelatedPropagation] `and X, C` wrongly replaced to `X (!range ...)`
|
| Labels |
|
| Assignees |
|
| Reporter |
bongjunj
|
https://github.com/llvm/llvm-project/blob/84ce230e4298672bb5247170d6183b31aa06fc4b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp#L1181-L1202
LHS could be `undef`.
Alive2 report: https://alive2.llvm.org/ce/z/7aNRWo
```llvm
----------------------------------------
define i16 @foo.2(i16 %x) {
#0:
%#1 = mul i16 %x, 65535
%t1 = and i16 %x, %#1
%t2 = zext i16 %t1 to i32
%t3 = icmp ult i32 %t2, 255
%t4 = select i1 %t3, i32 %t2, i32 255
%t5 = trunc i32 %t4 to i16
%t6 = and i16 %t5, 255
ret i16 %t6
}
=>
define i16 @foo.2(i16 %x) {
#0:
%#1 = mul i16 %x, 65535
%t1 = and i16 %x, %#1
%t2 = zext i16 %t1 to i32
%t3 = icmp ult i32 %t2, 255
%t4 = select i1 %t3, i32 %t2, i32 255
%t5 = trunc i32 %t4 to i16
%#range_0_%t5 = !range i16 %t5, i16 0, i16 256
ret i16 %#range_0_%t5
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i16 %x = undef
Source:
i16 %#1 = #x0000 (0) [based on undef value]
i16 %t1 = #x0000 (0)
i32 %t2 = #x00000000 (0)
i1 %t3 = #x1 (1)
i32 %t4 = #x00000000 (0) [based on undef value]
i16 %t5 = #x0000 (0)
i16 %t6 = #x0000 (0)
Target:
i16 %#1 = #x0000 (0)
i16 %t1 = #x0000 (0)
i32 %t2 = #x00000000 (0)
i1 %t3 = #x1 (1)
i32 %t4 = #x00007fff (32767)
i16 %t5 = #x7fff (32767)
i16 %#range_0_%t5 = poison
Source value: #x0000 (0)
Target value: poison
----------------------------------------
define i16 @foo.3(i16 %x) {
#0:
%#1 = add i16 %x, 255
%t2 = zext i16 %#1 to i32
%t3 = icmp ult i32 %t2, 255
%t4 = select i1 %t3, i32 %t2, i32 255
%t5 = trunc i32 %t4 to i16
%t6 = and i16 %t5, 255
ret i16 %t6
}
=>
define i16 @foo.3(i16 %x) {
#0:
%#1 = add i16 %x, 255
%t2 = zext i16 %#1 to i32
%t3 = icmp ult i32 %t2, 255
%t4 = select i1 %t3, i32 %t2, i32 255
%t5 = trunc i32 %t4 to i16
%#range_0_%t5 = !range i16 %t5, i16 0, i16 256
ret i16 %#range_0_%t5
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i16 %x = undef
Source:
i16 %#1 = #x00ff (255) [based on undef value]
i32 %t2 = #x000000ff (255)
i1 %t3 = #x0 (0)
i32 %t4 = #x000000ff (255)
i16 %t5 = #x00ff (255)
i16 %t6 = #x00ff (255)
Target:
i16 %#1 = #x007f (127)
i32 %t2 = #x0000007f (127)
i1 %t3 = #x1 (1)
i32 %t4 = #x00000100 (256)
i16 %t5 = #x0100 (256)
i16 %#range_0_%t5 = poison
Source value: #x00ff (255)
Target value: poison
----------------------------------------
define i16 @foo.4(i16 %x) {
#0:
%#1 = add i16 %x, 255
%#2 = sext i16 %#1 to i32
%t3 = icmp ult i32 %#2, 255
%t4 = select i1 %t3, i32 %#2, i32 255
%t5 = trunc i32 %t4 to i16
%t6 = and i16 %t5, 255
ret i16 %t6
}
=>
define i16 @foo.4(i16 %x) {
#0:
%#1 = add i16 %x, 255
%#2 = sext i16 %#1 to i32
%t3 = icmp ult i32 %#2, 255
%t4 = select i1 %t3, i32 %#2, i32 255
%t5 = trunc i32 %t4 to i16
%#range_0_%t5 = !range i16 %t5, i16 0, i16 256
ret i16 %#range_0_%t5
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i16 %x = undef
Source:
i16 %#1 = #x00ff (255) [based on undef value]
i32 %#2 = #x000000ff (255)
i1 %t3 = #x0 (0)
i32 %t4 = #x000000ff (255)
i16 %t5 = #x00ff (255)
i16 %t6 = #x00ff (255)
Target:
i16 %#1 = #x007f (127)
i32 %#2 = #x0000007f (127)
i1 %t3 = #x1 (1)
i32 %t4 = #x00000100 (256)
i16 %t5 = #x0100 (256)
i16 %#range_0_%t5 = poison
Source value: #x00ff (255)
Target value: poison
Summary:
0 correct transformations
3 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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