…en the loop contains control convergence operations. (#165643)

Skip constant folding the loop predicates if the loop contains control
convergence tokens referenced outside the loop.

Fixes #164496.

Verified
[loop_peeling.test](llvm/offload-test-suite#473)
passes with the fix.

Similar control convergence issues are found on other passes.
#165642

HLSL used for tests:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,1,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        if (i == TID.x) {
            Out[TID.x] = WaveActiveMax(TID.x);
            break;
        }
    }
}
```
With nested loop:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,8,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        for (uint j = 0; j < 8; j++) {
            if (i == TID.x && j == TID.y) {
                uint index = TID.x * 8 + TID.y;
                Out[index] = WaveActiveMax(index);
                break;
            }
        }
    }
}
```

…edicates when the loop contains control convergence operations. (#165643)

Skip constant folding the loop predicates if the loop contains control
convergence tokens referenced outside the loop.

Fixes llvm/llvm-project#164496.

Verified
[loop_peeling.test](llvm/offload-test-suite#473)
passes with the fix.

Similar control convergence issues are found on other passes.
llvm/llvm-project#165642

HLSL used for tests:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,1,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        if (i == TID.x) {
            Out[TID.x] = WaveActiveMax(TID.x);
            break;
        }
    }
}
```
With nested loop:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,8,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        for (uint j = 0; j < 8; j++) {
            if (i == TID.x && j == TID.y) {
                uint index = TID.x * 8 + TID.y;
                Out[index] = WaveActiveMax(index);
                break;
            }
        }
    }
}
```

…en the loop contains control convergence operations. (llvm#165643)

Skip constant folding the loop predicates if the loop contains control
convergence tokens referenced outside the loop.

Fixes llvm#164496.

Verified
[loop_peeling.test](llvm/offload-test-suite#473)
passes with the fix.

Similar control convergence issues are found on other passes.
llvm#165642

HLSL used for tests:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,1,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        if (i == TID.x) {
            Out[TID.x] = WaveActiveMax(TID.x);
            break;
        }
    }
}
```
With nested loop:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,8,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        for (uint j = 0; j < 8; j++) {
            if (i == TID.x && j == TID.y) {
                uint index = TID.x * 8 + TID.y;
                Out[index] = WaveActiveMax(index);
                break;
            }
        }
    }
}
```

…en the loop contains control convergence operations. (llvm#165643)

Skip constant folding the loop predicates if the loop contains control
convergence tokens referenced outside the loop.

Fixes llvm#164496.

Verified
[loop_peeling.test](llvm/offload-test-suite#473)
passes with the fix.

Similar control convergence issues are found on other passes.
llvm#165642

HLSL used for tests:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,1,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        if (i == TID.x) {
            Out[TID.x] = WaveActiveMax(TID.x);
            break;
        }
    }
}
```
With nested loop:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,8,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        for (uint j = 0; j < 8; j++) {
            if (i == TID.x && j == TID.y) {
                uint index = TID.x * 8 + TID.y;
                Out[index] = WaveActiveMax(index);
                break;
            }
        }
    }
}
```

…en the loop contains control convergence operations. (llvm#165643)

Skip constant folding the loop predicates if the loop contains control
convergence tokens referenced outside the loop.

Fixes llvm#164496.

Verified
[loop_peeling.test](llvm/offload-test-suite#473)
passes with the fix.

Similar control convergence issues are found on other passes.
llvm#165642

HLSL used for tests:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,1,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        if (i == TID.x) {
            Out[TID.x] = WaveActiveMax(TID.x);
            break;
        }
    }
}
```
With nested loop:
```hlsl
RWStructuredBuffer<uint> Out : register(u0);

[numthreads(8,8,1)]
void main(uint3 TID : SV_GroupThreadID) {
    for (uint i = 0; i < 8; i++) {
        for (uint j = 0; j < 8; j++) {
            if (i == TID.x && j == TID.y) {
                uint index = TID.x * 8 + TID.y;
                Out[index] = WaveActiveMax(index);
                break;
            }
        }
    }
}
```