[PATCH] D157373: [RISCV] add a compress optimization for stack inst.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp:1315
+      // riscv32: c.lwsp rd, offset[7:2] => 2^(6+2)
+      const uint64_t RV32CompressLen = 256;
+      // riscv64: c.lwsp rd, offset[8:3] => 2^(6+3)
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Can we compute CompressLen for both RV32 and RV64 as XLen * 8? And then merge the 2 if statements?


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Comment at: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp:1316
+      const uint64_t RV32CompressLen = 256;
+      // riscv64: c.lwsp rd, offset[8:3] => 2^(6+3)
+      const uint64_t RV64CompressLen = 512;
----------------
c.ldsp?


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Comment at: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp:1321
+                                  StackSize > 2048 * 3 - StackAlign))
+        FirstSPAmount = 256;
+      else if (STI.getXLen() == 64 && (StackSize <= RV64CompressLen + 2048 ||
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return 256


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Comment at: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp:1324
+                                       StackSize > 2048 * 3 - StackAlign))
+        FirstSPAmount = 512;
+    }
----------------
return 512


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Comment at: llvm/lib/Target/RISCV/RISCVFrameLowering.cpp:1326
+    }
+    return FirstSPAmount;
   }
----------------
return 2048 - StackAlign


Repository:
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  https://reviews.llvm.org/D157373/new/

https://reviews.llvm.org/D157373