[llvm] [RISCV] Pattern-match frameindex (NFCI) (PR #120917)

[Craig Topper via llvm-commits]

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@@ -1400,8 +1397,19 @@ def PseudoAddTPRel : Pseudo<(outs GPR:$rd),
 
 /// FrameIndex calculations
 
-def : Pat<(FrameAddrRegImm (iPTR GPR:$rs1), simm12:$imm12),
-          (ADDI GPR:$rs1, simm12:$imm12)>;
+// Converts frameindex -> tframeindex.
+def to_tframeindex : SDNodeXForm<frameindex, [{
+  return CurDAG->getTargetFrameIndex(N->getIndex(), N->getValueType(0));
+}]>;
+
+def : GICustomOperandRenderer<"renderFrameIndex">,
+      GISDNodeXFormEquiv<to_tframeindex>;
+
+def : Pat<(frameindex:$fi), (ADDI (iPTR (to_tframeindex $fi)), 0)>;
+
+def : Pat<(add_like frameindex:$fi, simm12:$offset),
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topperc wrote:

I think add_like might be less capable than `SelectionDAG::isBaseWithConstantOffset`, but if it shows up its probably fixable.

https://github.com/llvm/llvm-project/pull/120917