Int.sign_ext_shr_shl: weaker hypothesis

Works also for sign_ext 32.

ARM, RISC-V: adapt Asmgenproof1 accordingly

Author: xavierleroy

arm/Asmgenproof1.v

@@ -1218,7 +1218,7 @@ Proof.
   split. unfold rs2; Simpl. unfold rs1; Simpl.
   unfold Val.shr, Val.shl; destruct (rs x0); auto.
   change (Int.ltu (Int.repr 24) Int.iwordsize) with true; simpl.
-  f_equal. symmetry. apply (Int.sign_ext_shr_shl 8). compute; auto.
+  f_equal. symmetry. apply (Int.sign_ext_shr_shl 8). compute; intuition congruence.
   intros. unfold rs2, rs1; Simpl.
   (* Ocast16signed *)
   destruct Archi.thumb2_support.
@@ -1231,7 +1231,7 @@ Proof.
   split. unfold rs2; Simpl. unfold rs1; Simpl.
   unfold Val.shr, Val.shl; destruct (rs x0); auto.
   change (Int.ltu (Int.repr 16) Int.iwordsize) with true; simpl.
-  f_equal. symmetry. apply (Int.sign_ext_shr_shl 16). compute; auto.
+  f_equal. symmetry. apply (Int.sign_ext_shr_shl 16). compute; intuition congruence.
   intros. unfold rs2, rs1; Simpl.
   (* Oaddimm *)
   generalize (addimm_correct x x0 i k rs m).

lib/Integers.v

@@ -2766,7 +2766,7 @@ Qed.
 
 Corollary sign_ext_shr_shl:
   forall n x,
-  0 < n < zwordsize ->
+  0 < n <= zwordsize ->
   let y := repr (zwordsize - n) in
   sign_ext n x = shr (shl x y) y.
 Proof.
@@ -2801,7 +2801,7 @@ Qed.
 Lemma sign_ext_range:
   forall n x, 0 < n < zwordsize -> -two_p (n-1) <= signed (sign_ext n x) < two_p (n-1).
 Proof.
-  intros. rewrite sign_ext_shr_shl; auto.
+  intros. rewrite sign_ext_shr_shl by lia.
   set (X := shl x (repr (zwordsize - n))).
   assert (two_p (n - 1) > 0) by (apply two_p_gt_ZERO; lia).
   assert (unsigned (repr (zwordsize - n)) = zwordsize - n).

riscV/Asmgenproof1.v

@@ -1010,14 +1010,14 @@ Opaque Int.eq.
   split; intros; Simpl.
   assert (A: Int.ltu (Int.repr 24) Int.iwordsize = true) by auto.
   destruct (rs x0); auto; simpl. rewrite A; simpl. rewrite A. 
-  apply Val.lessdef_same. f_equal. apply Int.sign_ext_shr_shl. split; reflexivity.
+  apply Val.lessdef_same. f_equal. apply Int.sign_ext_shr_shl. compute; intuition congruence.
 - (* cast16signed *)
   econstructor; split.
   eapply exec_straight_two. simpl;eauto. simpl;eauto. auto. auto.
   split; intros; Simpl.
   assert (A: Int.ltu (Int.repr 16) Int.iwordsize = true) by auto.
   destruct (rs x0); auto; simpl. rewrite A; simpl. rewrite A. 
-  apply Val.lessdef_same. f_equal. apply Int.sign_ext_shr_shl. split; reflexivity.
+  apply Val.lessdef_same. f_equal. apply Int.sign_ext_shr_shl. compute; intuition congruence.
 - (* addimm *)
   exploit (opimm32_correct Paddw Paddiw Val.add); auto. instantiate (1 := x0); eauto with asmgen.
   intros (rs' & A & B & C).