[PATCH] D144956: Fix VGPR + offset Scratch offset folding

[Petar Avramovic via Phabricator via llvm-commits]

Petar.Avramovic added inline comments.


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Comment at: llvm/lib/Target/AMDGPU/AMDGPUISelDAGToDAG.cpp:1536-1537
       if (TII->isLegalFLATOffset(COffsetVal, AS, FlatVariant)) {
-        Addr = N0;
-        OffsetVal = COffsetVal;
+        // When value in 32-bit VGPR base can be negative calculate scratch
+        // offset using 32-bit add instruction,
+        // otherwise use vgpr base(unsigned) + offset.
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arsenm wrote:
> But the offsets are negative for scratch and global, isLegalFLATOffset should have accounted for this
isLegalFLATOffset checks for constant offset (the `+ offset`), this check is for value in register (the `base(unsigned)`) 


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  https://reviews.llvm.org/D144956/new/

https://reviews.llvm.org/D144956