[llvm] [RISCV] Use QC_E_ADDI while eliminating the frameindex (PR #139515)

[Craig Topper via llvm-commits]

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@@ -288,6 +288,17 @@ void RISCVRegisterInfo::adjustReg(MachineBasicBlock &MBB,
     return;
   }
 
+  // Use the QC_E_ADDI instruction from the Xqcilia extension that can take a
+  // signed 26-bit immediate. Avoid anything which can be done with a single lui
+  // as it might be compressible.
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topperc wrote:

Compressible LUI encodes a 6-bit immediate. So if the immediate is larger than simm18, it can never use c.lui even if the the lower 12 bits are 0.

https://github.com/llvm/llvm-project/pull/139515