s390x: clean up remnants of non-SSA code generation (#5096)

Eliminate a few remaining instances of non-SSA code.
Remove infrastructure previously used for non-SSA code emission.
Related cleanup around flags handling.

cranelift/filetests/filetests/isa/s390x/arithmetic.clif

@@ -1039,11 +1039,12 @@ block0(v0: i64, v1: i64):
 ; block0:
 ;   llihf %r4, 2147483647
 ;   iilf %r4, 4294967295
-;   xgrk %r5, %r4, %r2
-;   ngrk %r4, %r5, %r3
+;   xgr %r4, %r2
+;   lgr %r5, %r2
+;   ngr %r4, %r3
 ;   cgite %r4, -1
 ;   lgr %r4, %r3
-;   lgr %r3, %r2
+;   lgr %r3, %r5
 ;   dsgr %r2, %r4
 ;   lgr %r2, %r3
 ;   br %r14

cranelift/filetests/filetests/isa/s390x/bitops.clif

@@ -36,36 +36,34 @@ block0(v0: i64):
 }
 
 ; block0:
-;   lgr %r3, %r2
-;   llihf %r2, 2863311530
-;   iilf %r2, 2863311530
-;   lgr %r5, %r3
-;   sllg %r4, %r5, 1
-;   srlg %r3, %r5, 1
-;   ngr %r4, %r2
-;   xilf %r2, 4294967295
-;   xihf %r2, 4294967295
-;   ngrk %r2, %r3, %r2
-;   ogr %r4, %r2
-;   llihf %r3, 3435973836
-;   iilf %r3, 3435973836
-;   sllg %r5, %r4, 2
-;   srlg %r4, %r4, 2
+;   llihf %r3, 2863311530
+;   iilf %r3, 2863311530
+;   sllg %r5, %r2, 1
+;   srlg %r4, %r2, 1
+;   ngr %r5, %r3
+;   xilf %r3, 4294967295
+;   xihf %r3, 4294967295
+;   ngrk %r3, %r4, %r3
+;   ogrk %r2, %r5, %r3
+;   llihf %r5, 3435973836
+;   iilf %r5, 3435973836
+;   sllg %r3, %r2, 2
+;   srlg %r2, %r2, 2
+;   ngr %r3, %r5
+;   xilf %r5, 4294967295
+;   xihf %r5, 4294967295
+;   ngrk %r5, %r2, %r5
+;   ogrk %r4, %r3, %r5
+;   llihf %r3, 4042322160
+;   iilf %r3, 4042322160
+;   sllg %r5, %r4, 4
+;   srlg %r4, %r4, 4
 ;   ngr %r5, %r3
 ;   xilf %r3, 4294967295
 ;   xihf %r3, 4294967295
 ;   ngrk %r3, %r4, %r3
 ;   ogr %r5, %r3
-;   llihf %r4, 4042322160
-;   iilf %r4, 4042322160
-;   sllg %r2, %r5, 4
-;   srlg %r5, %r5, 4
-;   ngr %r2, %r4
-;   xilf %r4, 4294967295
-;   xihf %r4, 4294967295
-;   ngrk %r4, %r5, %r4
-;   ogr %r2, %r4
-;   lrvgr %r2, %r2
+;   lrvgr %r2, %r5
 ;   br %r14
 
 function %bitrev_i32(i32) -> i32 {

cranelift/filetests/filetests/isa/s390x/conversions.clif

@@ -334,9 +334,9 @@ block0(v0: i128):
 ;   vl %v0, 0(%r3)
 ;   vgbm %v5, 0
 ;   vceqgs %v7, %v0, %v5
-;   lghi %r3, 0
-;   locghine %r3, -1
-;   vlvgp %v21, %r3, %r3
+;   lghi %r4, 0
+;   locghine %r4, -1
+;   vlvgp %v21, %r4, %r4
 ;   vst %v21, 0(%r2)
 ;   br %r14
 
@@ -404,9 +404,9 @@ block0(v0: i64, v1: i64):
 
 ; block0:
 ;   cghi %r4, 0
-;   lghi %r4, 0
-;   locghilh %r4, -1
-;   vlvgp %v18, %r4, %r4
+;   lghi %r5, 0
+;   locghilh %r5, -1
+;   vlvgp %v18, %r5, %r5
 ;   vst %v18, 0(%r2)
 ;   br %r14
 
@@ -466,9 +466,9 @@ block0(v0: i32, v1: i32):
 
 ; block0:
 ;   chi %r4, 0
-;   lghi %r4, 0
-;   locghilh %r4, -1
-;   vlvgp %v18, %r4, %r4
+;   lghi %r5, 0
+;   locghilh %r5, -1
+;   vlvgp %v18, %r5, %r5
 ;   vst %v18, 0(%r2)
 ;   br %r14
 

cranelift/filetests/filetests/isa/s390x/div-traps.clif

@@ -17,13 +17,11 @@ block0(v0: i64, v1: i64):
 ;   llihf %r4, 2147483647
 ;   iilf %r4, 4294967295
 ;   xgr %r4, %r2
-;   lgr %r5, %r2
-;   ngr %r4, %r3
-;   lgr %r2, %r3
-;   cgite %r4, -1
-;   lgr %r4, %r2
-;   lgr %r3, %r5
-;   dsgr %r2, %r4
+;   ngrk %r5, %r4, %r3
+;   cgite %r5, -1
+;   lgr %r5, %r3
+;   lgr %r3, %r2
+;   dsgr %r2, %r5
 ;   lgr %r2, %r3
 ;   br %r14