[RISCV][GISEL] Legalize G_ZEXT, G_SEXT, and G_ANYEXT, G_SPLAT_VECTOR, and G_ICMP for scalable vector types

This patch legalizes G_ZEXT, G_SEXT, and G_ANYEXT. If the type is a
legal mask type, then the instruction is legalized as the element-wise
select, where the condition on the select is the mask typed source
operand, and the true and false values are 1 or -1 (for
zero/any-extension and sign extension) and zero. If the type is a legal integer
or vector integer type, then the instruction is marked as legal.

The legalization of the extends may introduce a G_SPLAT_VECTOR, which
needs to be legalized in this patch for the extend test cases to pass.

A G_SPLAT_VECTOR is legal if the vector type is a legal integer or
floating point vector type and the source operand is sXLen type. This is
because the SelectionDAG patterns only support sXLen typed
ISD::SPLAT_VECTORS, and we'd like to reuse those patterns. A
G_SPLAT_VECTOR is cutom legalized if it has a legal s1 element vector
type and s1 scalar operand. It is legalized to G_VMSET_VL or G_VMCLR_VL
if the splat is all ones or all zeros respectivley. In the case of a
non-constant mask splat, we legalize by promoting the scalar value to
s8.

In order to get the s8 element vector back into s1 vector, we use a
G_ICMP. In order for the splat vector and extend tests to pass, we also
need to legalize G_ICMP in this patch.

A G_ICMP is legal if the destination type is a legal bool vector and the LHS and
RHS are legal integer vector types.

2 files changed, 18 insertions, 8 deletions

diff --git a/llvm/test/MachineVerifier/test_g_fcmp.mir b/llvm/test/MachineVerifier/test_g_fcmp.mir
index 9a73569..17be746 100644
--- a/llvm/test/MachineVerifier/test_g_fcmp.mir
+++ b/llvm/test/MachineVerifier/test_g_fcmp.mir
@@ -24,17 +24,22 @@ body:             |
     %4:_(<2 x s32>) = G_IMPLICIT_DEF
     %5:_(s1) = G_FCMP floatpred(oeq), %3, %4
 
-    ; mismatched element count
+    ; mismatched fixed element count
     ; CHECK: Bad machine code: Generic vector icmp/fcmp must preserve number of
     %6:_(<2 x s32>) = G_IMPLICIT_DEF
     %7:_(<2 x s32>) = G_IMPLICIT_DEF
     %8:_(<4 x s1>) = G_FCMP floatpred(oeq), %6, %7
 
+    ; mismatched scalable element count
+    ; CHECK: Bad machine code: Generic vector icmp/fcmp must preserve number of
+    %9:_(<vscale x 2 x s32>) = G_IMPLICIT_DEF
+    %10:_(<vscale x 2 x s32>) = G_IMPLICIT_DEF
+    %11:_(<vscale x 4 x s1>) = G_FCMP floatpred(oeq), %9, %10
 
     ; mismatched scalar element type
     ; CHECK: *** Bad machine code: Type mismatch in generic instruction ***
-    %9:_(s32) = G_FCONSTANT float 0.0
-    %10:_(s64) = G_FCONSTANT float 1.0
-    %11:_(s1) = G_FCMP floatpred(oeq), %9, %10
+    %12:_(s32) = G_FCONSTANT float 0.0
+    %13:_(s64) = G_FCONSTANT float 1.0
+    %14:_(s1) = G_FCMP floatpred(oeq), %12, %13
 
 ...
diff --git a/llvm/test/MachineVerifier/test_g_icmp.mir b/llvm/test/MachineVerifier/test_g_icmp.mir
index 7c64e25..74e3d34 100644
--- a/llvm/test/MachineVerifier/test_g_icmp.mir
+++ b/llvm/test/MachineVerifier/test_g_icmp.mir
@@ -24,17 +24,22 @@ body:             |
     %4:_(<2 x s32>) = G_IMPLICIT_DEF
     %5:_(s1) = G_ICMP intpred(eq), %3, %4
 
-    ; mismatched element count
+    ; mismatched fixed element count
     ; CHECK: Bad machine code: Generic vector icmp/fcmp must preserve number of
     %6:_(<2 x s32>) = G_IMPLICIT_DEF
     %7:_(<2 x s32>) = G_IMPLICIT_DEF
     %8:_(<4 x s1>) = G_ICMP intpred(eq), %6, %7
 
+    ; mismatched scalable element count
+    ; CHECK: Bad machine code: Generic vector icmp/fcmp must preserve number of
+    %9:_(<vscale x 2 x s32>) = G_IMPLICIT_DEF
+    %10:_(<vscale x 2 x s32>) = G_IMPLICIT_DEF
+    %11:_(<vscale x 4 x s1>) = G_ICMP intpred(eq), %9, %10
 
     ; mismatched scalar element type
     ; CHECK: *** Bad machine code: Type mismatch in generic instruction ***
-    %9:_(s32) = G_CONSTANT i32 0
-    %10:_(s64) = G_CONSTANT i32 1
-    %11:_(s1) = G_ICMP intpred(eq), %9, %10
+    %12:_(s32) = G_CONSTANT i32 0
+    %13:_(s64) = G_CONSTANT i32 1
+    %14:_(s1) = G_ICMP intpred(eq), %12, %13
 
 ...