[RISCV][GlobalISel] Legalize G_FRAME_INDEX (#67746)

G_FRAME_INDEX is legal for pointers.

Author: nitinjohnraj

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

@@ -169,6 +169,8 @@ RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
 
   getActionDefinitionsBuilder(G_ABS).lower();
 
+  getActionDefinitionsBuilder(G_FRAME_INDEX).legalFor({p0});
+
   getLegacyLegalizerInfo().computeTables();
 }
 

llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rv32/legalize-frame-index.mir

@@ -0,0 +1,29 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv32 -run-pass=legalizer %s -o - \
+# RUN: | FileCheck %s
+--- |
+
+  define ptr @alloca32() {
+  entry:
+    %ptr0 = alloca i32, align 4
+    ret ptr %ptr0
+  }
+
+...
+---
+name:            alloca32
+stack:
+  - { id: 0, name: ptr0, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body:             |
+  bb.1.entry:
+    ; CHECK-LABEL: name: alloca32
+    ; CHECK: [[FRAME_INDEX:%[0-9]+]]:_(p0) = G_FRAME_INDEX %stack.0.ptr0
+    ; CHECK-NEXT: $x10 = COPY [[FRAME_INDEX]](p0)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(p0) = G_FRAME_INDEX %stack.0.ptr0
+    $x10 = COPY %0(p0)
+    PseudoRET implicit $x10
+
+...

llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rv64/legalize-frame-index.mir

@@ -0,0 +1,29 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=riscv32 -run-pass=legalizer %s -o - \
+# RUN: | FileCheck %s
+--- |
+
+  define ptr @alloca64() {
+  entry:
+    %ptr0 = alloca i64, align 4
+    ret ptr %ptr0
+  }
+
+...
+---
+name:            alloca64
+stack:
+  - { id: 0, name: ptr0, type: default, offset: 0, size: 4, alignment: 4,
+      stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
+body:             |
+  bb.1.entry:
+    ; CHECK-LABEL: name: alloca64
+    ; CHECK: [[FRAME_INDEX:%[0-9]+]]:_(p0) = G_FRAME_INDEX %stack.0.ptr0
+    ; CHECK-NEXT: $x10 = COPY [[FRAME_INDEX]](p0)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(p0) = G_FRAME_INDEX %stack.0.ptr0
+    $x10 = COPY %0(p0)
+    PseudoRET implicit $x10
+
+...