> You indeed need to use CONVERT_EXPR here, maybe you can elaborate
> on the optimization issues.
>
>> 2. for inline asm (a reduced test case that might not make much as a
>> stand alone test-case, but I ran into similar cases with valid programmes)
>>
>> ;; Function fn1 (fn1, funcdef_no=0, decl_uid=4220, cgraph_uid=0,
>> symbol_order=0)
>>
>> fn1 (short int p1)
>> {
>>    <bb 2>:
>>    __asm__("" : "=r" p1_2 : "0" p1_1(D));
>>    return;
>>
>> }
>>
>>
>> I am generating something like the following which ICEs. What is the
>> expected out?
>>
>> ;; Function fn1 (fn1, funcdef_no=0, decl_uid=4220, cgraph_uid=0,
>> symbol_order=0)
>>
>> fn1 (short int p1)
>> {
>>    int _1;
>>    int _2;
>>    short int _5;
>>
>>    <bb 2>:
>>    _1 = (int) p1_4(D);
>>    _5 = (short int) _1;
>>    __asm__("" : "=r" p1_6 : "0" _5);
>>    _2 = (int) p1_6;
>>    return;
>>
>> }
>
> Parameters are indeed "interesting" to handle ;)  As we now see on ARM
> the incoming parameter (the default def) and later assignments to it
> can require different promotions (well, different extensions for ARM).
>
> The only sensible way to deal with promoting parameters is to
> promote them by changing the function signature.  Thus reflect the
> targets ABI for parameters in the GIMPLE representation (which
> includes TYPE_ARG_TYPES and DECL_ARGUMENTS).
> IMHO we should do this during gimplification of parameters / call
> arguments already.
>
> So for your example you'd end up with
>
> fn1 (int p1)
> {
>    __asm__("" : "=r" p1_6 : "0" p1_4(D));
>    return;
> }
>
> that is, promotions also apply to asm inputs/outputs (no?)


Thanks for the review and answers. For the time being, I am handling 
gimple_asm as one that has to be handled in original type. I Will look 
into improving it after getting the basic framework right.

As it is, attached patch bootstraps on x86_64-linux-gnu, arm-linux-gnu 
and aarch64-linux-gnu. There are few regressions to look into (Please 
see below).

There are cases it is working well. There are cases where it can be 
improved. I am attaching couple test cases (and their results). I am 
seeing some BIT_AND_EXPR which are inserted by promotion are not being 
optimized when they are redundant. This is especially the case when I 
invalidate the VRP range into from VRP1 during the type promotion. I am 
looking into it.

Please note that attached patch still needs to address:
* Adding gimple_debug stmts.
* Address review comment for expr.c handling SEXT_EXPR.
* Address regression failures

Based on the feedback, I will address the above and split the patch into 
logical patch set for easy detailed review.

Here are the outputs for the testcases.

--- c5.c.142t.veclower21	2015-08-05 08:50:11.367135339 +1000
+++ c5.c.143t.promotion	2015-08-05 08:50:11.367135339 +1000
@@ -1,34 +1,45 @@

  ;; Function unPack (unPack, funcdef_no=0, decl_uid=4145, cgraph_uid=0, 
symbol_order=0)

  unPack (unsigned char c)
  {
-  short int _1;
-  unsigned short _4;
-  unsigned short _5;
-  short int _6;
-  short int _7;
+  int _1;
+  unsigned int _2;
+  unsigned int _3;
+  unsigned int _4;
+  unsigned int _5;
+  int _6;
+  int _7;
+  unsigned int _9;
+  int _11;
+  int _12;
+  short int _13;

    <bb 2>:
-  c_3 = c_2(D) & 15;
-  if (c_3 > 7)
+  _2 = (unsigned int) c_10(D);
+  _3 = _2 & 15;
+  _9 = _3 & 255;
+  if (_9 > 7)
      goto <bb 3>;
    else
      goto <bb 4>;

    <bb 3>:
-  _4 = (unsigned short) c_3;
-  _5 = _4 + 65531;
-  _6 = (short int) _5;
+  _4 = _3 & 65535;
+  _5 = _4 + 4294967291;
+  _11 = (int) _5;
+  _6 = (_11) sext from bit (16);
    goto <bb 5>;

    <bb 4>:
-  _7 = (short int) c_3;
+  _12 = (int) _3;
+  _7 = (_12) sext from bit (16);

    <bb 5>:
    # _1 = PHI <_6(3), _7(4)>
-  return _1;
+  _13 = (short int) _1;
+  return _13;

  }


--- c5.org.s	2015-08-05 08:51:44.619133892 +1000
+++ c5.new.s	2015-08-05 08:51:29.643134124 +1000
@@ -16,16 +16,14 @@
  	.syntax divided
  	.arm
  	.type	unPack, %function
  unPack:
  	@ args = 0, pretend = 0, frame = 0
  	@ frame_needed = 0, uses_anonymous_args = 0
  	@ link register save eliminated.
  	and	r0, r0, #15
  	cmp	r0, #7
  	subhi	r0, r0, #5
-	uxth	r0, r0
-	sxth	r0, r0
  	bx	lr
  	.size	unPack, .-unPack
  	.ident	"GCC: (GNU) 6.0.0 20150724 (experimental)"
  	.section	.note.GNU-stack,"",%progbits
--- crc.c.142t.veclower21	2015-08-05 08:52:43.811132974 +1000
+++ crc.c.143t.promotion	2015-08-05 08:52:43.811132974 +1000
@@ -1,52 +1,78 @@

  ;; Function crc2 (crc2, funcdef_no=0, decl_uid=4146, cgraph_uid=0, 
symbol_order=0)

  crc2 (short unsigned int crc, unsigned char data)
  {
    unsigned char carry;
    unsigned char x16;
    unsigned char i;
-  unsigned char ivtmp_5;
-  unsigned char _9;
-  unsigned char _10;
-  unsigned char ivtmp_18;
+  unsigned int _2;
+  unsigned int _3;
+  unsigned int _5;
+  unsigned int _7;
+  unsigned int _8;
+  unsigned int _9;
+  unsigned int _10;
+  unsigned int _11;
+  unsigned int _12;
+  unsigned int _13;
+  unsigned int _15;
+  unsigned int _16;
+  unsigned int _18;
+  unsigned int _19;
+  unsigned int _21;
+  unsigned int _22;
+  unsigned int _24;
+  short unsigned int _25;
+  unsigned int _26;
+  unsigned int _27;
+  unsigned int _28;
+  unsigned int _29;

    <bb 2>:
+  _8 = (unsigned int) data_4(D);
+  _7 = (unsigned int) crc_30(D);

    <bb 3>:
-  # crc_28 = PHI <crc_2(5), crc_7(D)(2)>
-  # data_29 = PHI <data_12(5), data_8(D)(2)>
-  # ivtmp_18 = PHI <ivtmp_5(5), 8(2)>
-  _9 = (unsigned char) crc_28;
-  _10 = _9 ^ data_29;
-  x16_11 = _10 & 1;
-  data_12 = data_29 >> 1;
-  if (x16_11 == 1)
+  # _28 = PHI <_2(5), _7(2)>
+  # _29 = PHI <_12(5), _8(2)>
+  # _18 = PHI <_5(5), 8(2)>
+  _9 = _28 & 255;
+  _10 = _9 ^ _29;
+  _11 = _10 & 1;
+  _3 = _29 & 255;
+  _12 = _3 >> 1;
+  _27 = _11 & 255;
+  if (_27 == 1)
      goto <bb 4>;
    else
      goto <bb 7>;

    <bb 4>:
-  crc_13 = crc_28 ^ 16386;
-  crc_24 = crc_13 >> 1;
-  crc_15 = crc_24 | 32768;
+  _13 = _28 ^ 16386;
+  _26 = _13 & 65535;
+  _24 = _26 >> 1;
+  _15 = _24 | 4294934528;

    <bb 5>:
-  # crc_2 = PHI <crc_15(4), crc_21(7)>
-  ivtmp_5 = ivtmp_18 - 1;
-  if (ivtmp_5 != 0)
+  # _2 = PHI <_15(4), _21(7)>
+  _5 = _18 - 1;
+  _22 = _5 & 255;
+  if (_22 != 0)
      goto <bb 3>;
    else
      goto <bb 6>;

    <bb 6>:
-  # crc_19 = PHI <crc_2(5)>
-  return crc_19;
+  # _19 = PHI <_2(5)>
+  _25 = (short unsigned int) _19;
+  return _25;

    <bb 7>:
-  crc_21 = crc_28 >> 1;
+  _16 = _28 & 65535;
+  _21 = _16 >> 1;
    goto <bb 5>;

  }


--- crc.org.s	2015-08-05 08:54:17.491131520 +1000
+++ crc.new.s	2015-08-05 08:53:12.183132534 +1000
@@ -15,27 +15,28 @@
  	.global	crc2
  	.syntax divided
  	.arm
  	.type	crc2, %function
  crc2:
  	@ args = 0, pretend = 0, frame = 0
  	@ frame_needed = 0, uses_anonymous_args = 0
  	mov	ip, #32768
  	movt	ip, 65535
  	str	lr, [sp, #-4]!
-	mov	r3, #8
+	mov	r2, #8
  	movw	lr, #16386
  .L3:
-	eor	r2, r1, r0
-	sub	r3, r3, #1
-	tst	r2, #1
+	uxtb	r3, r0
+	eor	r3, r3, r1
  	mov	r1, r1, lsr #1
+	tst	r3, #1
  	eorne	r0, r0, lr
-	moveq	r0, r0, lsr #1
-	orrne	r0, ip, r0, lsr #1
-	uxthne	r0, r0
-	ands	r3, r3, #255
+	ubfxeq	r0, r0, #1, #15
+	ubfxne	r0, r0, #1, #15
+	orrne	r0, r0, ip
+	subs	r2, r2, #1
  	bne	.L3
+	uxth	r0, r0
  	ldr	pc, [sp], #4
  	.size	crc2, .-crc2
  	.ident	"GCC: (GNU) 6.0.0 20150724 (experimental)"
  	.section	.note.GNU-stack,"",%progbits



Testsuite regression for x86_64-unknown-linux-gnu:
Tests that now fail, but worked before:
gfortran.dg/graphite/pr42393-1.f90   -O  (test for excess errors)


Testsuite regression for  arm-linux-gnu:
Tests that now fail, but worked before:
arm-sim: gcc.dg/fixed-point/convert-sat.c execution test
arm-sim: gcc.dg/tree-ssa/20030729-1.c scan-tree-dump-times dom2 "\\(unsigned
int\\)" 0
arm-sim: gcc.dg/tree-ssa/pr54245.c scan-tree-dump-times slsr "Inserting
initializer" 0
arm-sim: gcc.dg/tree-ssa/shorten-1.c scan-tree-dump-not optimized
"\\(int\\)"
arm-sim: gcc.dg/tree-ssa/shorten-1.c scan-tree-dump-times optimized
"\\(unsigned char\\)" 8
arm-sim: gcc.target/arm/mla-2.c scan-assembler smlalbb
arm-sim: gcc.target/arm/unsigned-extend-2.c scan-assembler ands
arm-sim: gcc.target/arm/wmul-1.c scan-assembler-times smlabb 2
arm-sim: gcc.target/arm/wmul-2.c scan-assembler-times smulbb 1
arm-sim: gcc.target/arm/wmul-3.c scan-assembler-times smulbb 2
arm-sim: gcc.target/arm/wmul-9.c scan-assembler smlalbb
arm-sim: gfortran.dg/graphite/pr42393-1.f90   -O  (test for excess errors)

Tests that now work, but didn't before:
arm-sim: gcc.dg/tree-prof/time-profiler-2.c scan-ipa-dump-times profile
"Read tp_first_run: 0" 2
arm-sim: gcc.dg/tree-prof/time-profiler-2.c scan-ipa-dump-times profile
"Read tp_first_run: 2" 1
arm-sim: gcc.dg/tree-prof/time-profiler-2.c scan-ipa-dump-times profile
"Read tp_first_run: 3" 1
arm-sim: gcc.target/arm/builtin-bswap-1.c scan-assembler-times rev16ne\\t 1
arm-sim: gcc.target/arm/builtin-bswap-1.c scan-assembler-times revshne\\t 1
arm-sim: gcc.target/arm/smlaltb-1.c scan-assembler smlaltb\\t
arm-sim: gcc.target/arm/smlaltt-1.c scan-assembler smlaltt\\t


Testsuite regression for  aarch64-linux-gnu:
Tests that now fail, but worked before:
c-c++-common/torture/vector-compare-1.c   -O3 -g  (test for excess errors)
c-c++-common/torture/vector-compare-1.c   -O3 -g  (test for excess errors)
gcc.dg/tree-ssa/20030729-1.c scan-tree-dump-times dom2 "\\(unsigned int\\)"
0
gcc.dg/tree-ssa/pr54245.c scan-tree-dump-times slsr "Inserting initializer"
0
gcc.dg/tree-ssa/shorten-1.c scan-tree-dump-not optimized "\\(int\\)"
gcc.dg/tree-ssa/shorten-1.c scan-tree-dump-times optimized "\\(unsigned
char\\)" 8

Thanks,
Kugan