Revert "[AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition copies"

This reverts commit r286171, it breaks piglit test fs-discard-exit-2

llvm-svn: 286530

[AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition copies

Codegen prepare sinks comparisons close to a user is we have only one register
for conditions. For AMDGPU we have

[AMDGPU] Allow hoisting of comparisons out of a loop and eliminate condition copies

Codegen prepare sinks comparisons close to a user is we have only one register
for conditions. For AMDGPU we have many SGPRs capable to hold vector conditions.
Changed BE to report we have many condition registers. That way IR LICM pass
would hoist an invariant comparison out of a loop and codegen prepare will not
sink it.

With that done a condition is calculated in one block and used in another.
Current behavior is to store workitem's condition in a VGPR using v_cndmask
and then restore it with yet another v_cmp instruction from that v_cndmask's
result. To mitigate the issue a forward propagation of a v_cmp 64 bit result
to an user is implemented. Additional side effect of this is that we may
consume less VGPRs in a cost of more SGPRs in case if holding of multiple
conditions is needed, and that is a clear win in most cases.

llvm-svn: 286171

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Use StringRef in Pass/PassManager APIs (NFC)

llvm-svn: 283004

AMDGPU: Use unsigned compare for eq/ne

For some reason there are both of these available, except
for scalar 64-bit compares which only has u64. I'm not sure
why there are both (I'm guessing it's for

AMDGPU: Use unsigned compare for eq/ne

For some reason there are both of these available, except
for scalar 64-bit compares which only has u64. I'm not sure
why there are both (I'm guessing it's for the one bit inputs we
don't use), but for consistency always using the
unsigned one.

llvm-svn: 282832

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AMDGPU: Cleanup subtarget handling.

Split AMDGPUSubtarget into amdgcn/r600 specific subclasses.
This removes most of the static_casting of the basic codegen
classes everywhere, and tries to restrict

AMDGPU: Cleanup subtarget handling.

Split AMDGPUSubtarget into amdgcn/r600 specific subclasses.
This removes most of the static_casting of the basic codegen
classes everywhere, and tries to restrict the features
visible on the wrong target.

llvm-svn: 273652

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AMDGPU: Fix passes depending on dominator tree for no reason

llvm-svn: 260494

AMDGPU: Fix recomputing dominator tree unnecessarily

SIFixSGPRCopies does not modify the CFG, but this was
being recomputed before running SIFoldOperands.

llvm-svn: 248587

R600 -> AMDGPU rename

llvm-svn: 239657