| Issue |
113997
|
| Summary |
[GVNPass] Range attribute should be handled after CSE
|
| Labels |
miscompilation,
llvm:transforms
|
| Assignees |
|
| Reporter |
dtcxzyw
|
Reproducer: https://alive2.llvm.org/ce/z/HAnoKn
```
define i1 @src(i32 noundef %x) {
%cmp1 = icmp sgt i32 %x, 0
%ctpop1 = tail call range(i32 1, 32) i32 @llvm.ctpop.i32(i32 %x)
%cmp2 = icmp samesign ult i32 %ctpop1, 2
%cond = select i1 %cmp1, i1 %cmp2, i1 false
br i1 %cond, label %if.then, label %if.else
if.else:
%ctpop2 = tail call range(i32 0, 33) i32 @llvm.ctpop.i32(i32 %x)
%res = icmp eq i32 %ctpop2, 1
ret i1 %res
if.then:
ret i1 false
}
define i1 @tgt(i32 noundef %x) {
%cmp1 = icmp sgt i32 %x, 0
%ctpop1 = tail call range(i32 1, 32) i32 @llvm.ctpop.i32(i32 %x)
%cmp2 = icmp samesign ult i32 %ctpop1, 2
%cond = select i1 %cmp1, i1 %cmp2, i1 false
br i1 %cond, label %if.then, label %if.else
if.else:
%res = icmp eq i32 %ctpop1, 1
ret i1 %res
if.then:
ret i1 false
}
```
```
----------------------------------------
define i1 @src(i32 noundef %x) {
#0:
%cmp1 = icmp sgt i32 noundef %x, 0
%ctpop1 = ctpop i32 noundef %x
%#range_0_%ctpop1 = !range i32 %ctpop1, i32 1, i32 32
%cmp2 = icmp samesign ult i32 %#range_0_%ctpop1, 2
%cond = select i1 %cmp1, i1 %cmp2, i1 0
br i1 %cond, label %if.then, label %if.else
if.else:
%ctpop2 = ctpop i32 noundef %x
%#range_1_%ctpop2 = !range i32 %ctpop2, i32 0, i32 33
%res = icmp eq i32 %#range_1_%ctpop2, 1
ret i1 %res
if.then:
ret i1 0
}
=>
define i1 @tgt(i32 noundef %x) {
#0:
%cmp1 = icmp sgt i32 noundef %x, 0
%ctpop1 = ctpop i32 noundef %x
%#range_0_%ctpop1 = !range i32 %ctpop1, i32 1, i32 32
%cmp2 = icmp samesign ult i32 %#range_0_%ctpop1, 2
%cond = select i1 %cmp1, i1 %cmp2, i1 0
br i1 %cond, label %if.then, label %if.else
if.else:
%res = icmp eq i32 %#range_0_%ctpop1, 1
ret i1 %res
if.then:
ret i1 0
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source
Example:
i32 noundef %x = #x00000000 (0)
Source:
i1 %cmp1 = #x0 (0)
i32 %ctpop1 = #x00000000 (0)
i32 %#range_0_%ctpop1 = poison
i1 %cmp2 = poison
i1 %cond = #x0 (0)
>> Jump to %if.else
i32 %ctpop2 = #x00000000 (0)
i32 %#range_1_%ctpop2 = #x00000000 (0)
i1 %res = #x0 (0)
Target:
i1 %cmp1 = #x0 (0)
i32 %ctpop1 = #x00000000 (0)
i32 %#range_0_%ctpop1 = poison
i1 %cmp2 = poison
i1 %cond = #x0 (0)
>> Jump to %if.else
i1 %res = poison
Source value: #x0 (0)
Target value: poison
```
Reported by @pranavk. See https://github.com/llvm/llvm-project/pull/100899#issuecomment-2442780517.
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