[llvm] [ARM] Add size to `tLDRLIT_ga_pcrel` Pseudo Instructoin (PR #175663)

[Peter Smith via llvm-commits]

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@@ -1605,7 +1605,9 @@ def tLDRLIT_ga_pcrel : PseudoInst<(outs tGPR:$dst), (ins i32imm:$addr),
                                   IIC_iLoadiALU,
                                   [(set tGPR:$dst,
                                         (ARMWrapperPIC tglobaladdr:$addr))]>,
-                       Requires<[IsThumb, DontUseMovtInPic]>;
+                       Requires<[IsThumb, DontUseMovtInPic]> {
+  let Size = 8;  // 2 instructions + constant.
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smithp35 wrote:

Looking at the example I have again, the constant pool entries were created by legalization and were using `tLDRpci` rather than a pseudo. I agree that if the constant pool entries haven't been created yet then they'll need to be accounted for in the instruction size for the benefit of the size estimate.

https://github.com/llvm/llvm-project/pull/175663