--- /dev/null
+; RUN: llc < %s -mtriple=arm64-apple-darwin | FileCheck %s
+
+; PR20778
+; Check that the legalizer doesn't crash when scalarizing FP conversion
+; instructions' operands. The operands are all illegal on AArch64,
+; ensuring they are legalized. The results are all legal.
+
+define <1 x double> @test_sitofp(<1 x i1> %in) {
+; CHECK-LABEL: test_sitofp:
+; CHECK: sbfx w8, w0, #0, #1
+; CHECK-NEXT: scvtf d0, w8
+; CHECK-NEXT: ret
+entry:
+ %0 = sitofp <1 x i1> %in to <1 x double>
+ ret <1 x double> %0
+}
+
+define <1 x double> @test_uitofp(<1 x i1> %in) {
+; CHECK-LABEL: test_uitofp:
+; CHECK: and w8, w0, #0x1
+; CHECK-NEXT: ucvtf d0, w8
+; CHECK-NEXT: ret
+entry:
+ %0 = uitofp <1 x i1> %in to <1 x double>
+ ret <1 x double> %0
+}
+
+define <1 x i64> @test_fptosi(<1 x fp128> %in) {
+; CHECK-LABEL: test_fptosi:
+; CHECK: bl ___fixtfdi
+; CHECK-NEXT: fmov d0, x0
+entry:
+ %0 = fptosi <1 x fp128> %in to <1 x i64>
+ ret <1 x i64> %0
+}
+
+define <1 x i64> @test_fptoui(<1 x fp128> %in) {
+; CHECK-LABEL: test_fptoui:
+; CHECK: bl ___fixunstfdi
+; CHECK-NEXT: fmov d0, x0
+entry:
+ %0 = fptoui <1 x fp128> %in to <1 x i64>
+ ret <1 x i64> %0
+}