[X86] Add test coverage for zext(or(shl_nuw(x,c1),c2)) pointer math

Additional test coverage for D155472

Author: RKSimon

llvm/test/CodeGen/X86/addr-mode-matcher-3.ll

@@ -0,0 +1,28 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-unknown | FileCheck %s --check-prefix=X86
+; RUN: llc < %s -mtriple=x86_64-unknown | FileCheck %s --check-prefix=X64
+
+define i32 @mask_offset_scale_i32_i64(ptr %base, i32 %i) {
+; X86-LABEL: mask_offset_scale_i32_i64:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    movzbl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    shll $11, %ecx
+; X86-NEXT:    movl 48(%eax,%ecx), %eax
+; X86-NEXT:    retl
+;
+; X64-LABEL: mask_offset_scale_i32_i64:
+; X64:       # %bb.0:
+; X64-NEXT:    # kill: def $esi killed $esi def $rsi
+; X64-NEXT:    andl $65280, %esi # imm = 0xFF00
+; X64-NEXT:    addl %esi, %esi
+; X64-NEXT:    movl 48(%rdi,%rsi,4), %eax
+; X64-NEXT:    retq
+  %mask = and i32 %i, 65280
+  %offset = or i32 %mask, 6
+  %scale = shl i32 %offset, 1
+  %idxprom = zext i32 %scale to i64
+  %arrayidx = getelementptr inbounds i32, ptr %base, i64 %idxprom
+  %load = load i32, ptr %arrayidx, align 4
+  ret i32 %load
+}