| Issue |
120823
|
| Summary |
[SLPVectorizer] `samesign` flags should be dropped after narrowing down the width of operands
|
| Labels |
miscompilation,
llvm:SLPVectorizer
|
| Assignees |
|
| Reporter |
dtcxzyw
|
Reproducer: https://alive2.llvm.org/ce/z/AvBhy9
```
; bin/opt -passes=slp-vectorizer test.ll -S
target triple = "x86_64-unknown-linux-gnu"
define i1 @test() {
entry:
%and.i1698.1.i = zext i16 0 to i32
%and19.i1699.2.i = and i32 %and.i1698.1.i, 0
%and.i1698.2.i = zext i16 0 to i32
%cmp25.i1700.2.i2 = icmp samesign uge i32 %and19.i1699.2.i, %and.i1698.1.i
%and19.i1699.11841.i = and i32 %and.i1698.2.i, 0
%cmp25.i1700.11842.i3 = icmp samesign uge i32 %and19.i1699.11841.i, %and.i1698.2.i
%and.i1698.1.1.i = zext i16 0 to i32
%and19.i1699.2.1.i = and i32 %and.i1698.1.1.i, 0
%0 = add i16 1, 0
%and.i1698.2.1.i = zext i16 %0 to i32
%cmp25.i1700.2.1.i4 = icmp samesign uge i32 %and19.i1699.2.1.i, %and.i1698.1.1.i
%and19.i1699.21846.i = and i32 %and.i1698.2.1.i, 0
%cmp25.i1700.21847.i = icmp samesign uge i32 %and19.i1699.21846.i, %and.i1698.2.1.i
ret i1 %cmp25.i1700.21847.i
}
```
```
define i1 @test() {
entry:
%0 = add i16 1, 0
%1 = insertelement <4 x i16> <i16 poison, i16 0, i16 0, i16 0>, i16 %0, i32 0
%2 = trunc <4 x i16> %1 to <4 x i1>
%3 = and <4 x i1> %2, zeroinitializer
%4 = icmp samesign uge <4 x i1> %3, %2
%5 = extractelement <4 x i1> %4, i32 0
ret i1 %5
}
```
```
----------------------------------------
define i1 @src() {
entry:
%#0 = add i16 1, 0
%and.i1698.2.1.i = zext i16 %#0 to i32
%and19.i1699.21846.i = and i32 %and.i1698.2.1.i, 0
%cmp25.i1700.21847.i = icmp samesign uge i32 %and19.i1699.21846.i, %and.i1698.2.1.i
ret i1 %cmp25.i1700.21847.i
}
=>
define i1 @src() {
entry:
%#0 = add i16 1, 0
%#1 = insertelement <4 x i16> { poison, 0, 0, 0 }, i16 %#0, i32 0
%#2 = trunc <4 x i16> %#1 to <4 x i1>
%#3 = and <4 x i1> %#2, { 0, 0, 0, 0 }
%#4 = icmp samesign uge <4 x i1> %#3, %#2
%#5 = extractelement <4 x i1> %#4, i32 0
ret i1 %#5
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
Source:
i16 %#0 = #x0001 (1)
i32 %and.i1698.2.1.i = #x00000001 (1)
i32 %and19.i1699.21846.i = #x00000000 (0)
i1 %cmp25.i1700.21847.i = #x0 (0)
Target:
i16 %#0 = #x0001 (1)
<4 x i16> %#1 = < #x0001 (1), #x0000 (0), #x0000 (0), #x0000 (0) >
<4 x i1> %#2 = < #x1 (1), #x0 (0), #x0 (0), #x0 (0) >
<4 x i1> %#3 = < #x0 (0), #x0 (0), #x0 (0), #x0 (0) >
<4 x i1> %#4 = < poison, #x1 (1), #x1 (1), #x1 (1) >
i1 %#5 = poison
Source value: #x0 (0)
Target value: poison
Summary:
0 correct transformations
1 incorrect transformations
0 failed-to-prove transformations
0 Alive2 errors
```
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