AMDGPU: Change API for checking for exec modification

Invert the name and return value to better reflect the imprecise
nature.

Force passing in the DefMI, since it's known in the 2 users and could
possibly fail for an arbitrary vreg.

Allow specifying a specific user instruction. Scan through use
instructions, instead of use operands. Add scan thresholds instead of
searching infinitely.

Stop using a set to track seen uses. I didn't understand this usage,
or why it would not check the last use. I don't think the use list has
any particular order.

llvm-svn: 363675

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/AMDGPU/GCNDPPCombine.cpp b/llvm/lib/Target/AMDGPU/GCNDPPCombine.cpp
index 430cf480eb1..fb1d71779cb 100644
--- a/llvm/lib/Target/AMDGPU/GCNDPPCombine.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNDPPCombine.cpp
@@ -331,7 +331,7 @@ bool GCNDPPCombine::combineDPPMov(MachineInstr &MovMI) const {
   auto *DstOpnd = TII->getNamedOperand(MovMI, AMDGPU::OpName::vdst);
   assert(DstOpnd && DstOpnd->isReg());
   auto DPPMovReg = DstOpnd->getReg();
-  if (!isEXECMaskConstantBetweenDefAndUses(DPPMovReg, *MRI)) {
+  if (execMayBeModifiedBeforeUse(*MRI, DPPMovReg, MovMI)) {
     LLVM_DEBUG(dbgs() << "  failed: EXEC mask should remain the same"
                          " for all uses\n");
     return false;