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Fix -(x > y) on ARM
- From: Richard Earnshaw <Richard dot Earnshaw at buzzard dot freeserve dot co dot uk>
- To: gcc-patches at gcc dot gnu dot org
- Date: Sat, 23 Jun 2007 19:10:48 +0100
- Subject: Fix -(x > y) on ARM
This is somewhat embarrassing, since this bug has been there since about
1994 (ie circa gcc-2.5). We were generating incorrect code for -(X >
Y). We also had an incorrect test for -(X < 0) which meant that the
optimization was never applied. Fixed with the patch below and new
testcase added.
R.
2007-06-23 Richard Earnshaw <rearnsha@arm.com>
PR target/31152
* arm.md (negscc): Match the correct operand for optimized LT0 test.
Remove optimization for GT.
* gcc.c-torture/execute/20070623-1.c: New.
*** config/arm/arm.md (revision 126009)
--- config/arm/arm.md (local)
*************** (define_insn "*negscc"
*** 9423,9437 ****
(clobber (reg:CC CC_REGNUM))]
"TARGET_ARM"
"*
! if (GET_CODE (operands[3]) == LT && operands[3] == const0_rtx)
return \"mov\\t%0, %1, asr #31\";
if (GET_CODE (operands[3]) == NE)
return \"subs\\t%0, %1, %2\;mvnne\\t%0, #0\";
- if (GET_CODE (operands[3]) == GT)
- return \"subs\\t%0, %1, %2\;mvnne\\t%0, %0, asr #31\";
-
output_asm_insn (\"cmp\\t%1, %2\", operands);
output_asm_insn (\"mov%D3\\t%0, #0\", operands);
return \"mvn%d3\\t%0, #0\";
--- 9423,9434 ----
(clobber (reg:CC CC_REGNUM))]
"TARGET_ARM"
"*
! if (GET_CODE (operands[3]) == LT && operands[2] == const0_rtx)
return \"mov\\t%0, %1, asr #31\";
if (GET_CODE (operands[3]) == NE)
return \"subs\\t%0, %1, %2\;mvnne\\t%0, #0\";
output_asm_insn (\"cmp\\t%1, %2\", operands);
output_asm_insn (\"mov%D3\\t%0, #0\", operands);
return \"mvn%d3\\t%0, #0\";
*** testsuite/gcc.c-torture/execute/20070623-1.c (revision 126009)
--- testsuite/gcc.c-torture/execute/20070623-1.c (local)
***************
*** 0 ****
--- 1,41 ----
+ #include <limits.h>
+
+ int __attribute__((noinline)) nge(int a, int b) {return -(a >= b);}
+ int __attribute__((noinline)) ngt(int a, int b) {return -(a > b);}
+ int __attribute__((noinline)) nle(int a, int b) {return -(a <= b);}
+ int __attribute__((noinline)) nlt(int a, int b) {return -(a < b);}
+ int __attribute__((noinline)) neq(int a, int b) {return -(a == b);}
+ int __attribute__((noinline)) nne(int a, int b) {return -(a != b);}
+ int __attribute__((noinline)) ngeu(unsigned a, unsigned b) {return -(a >= b);}
+ int __attribute__((noinline)) ngtu(unsigned a, unsigned b) {return -(a > b);}
+ int __attribute__((noinline)) nleu(unsigned a, unsigned b) {return -(a <= b);}
+ int __attribute__((noinline)) nltu(unsigned a, unsigned b) {return -(a < b);}
+
+
+ int main()
+ {
+ if (nge(INT_MIN, INT_MAX) != 0) abort();
+ if (nge(INT_MAX, INT_MIN) != -1) abort();
+ if (ngt(INT_MIN, INT_MAX) != 0) abort();
+ if (ngt(INT_MAX, INT_MIN) != -1) abort();
+ if (nle(INT_MIN, INT_MAX) != -1) abort();
+ if (nle(INT_MAX, INT_MIN) != 0) abort();
+ if (nlt(INT_MIN, INT_MAX) != -1) abort();
+ if (nlt(INT_MAX, INT_MIN) != 0) abort();
+
+ if (neq(INT_MIN, INT_MAX) != 0) abort();
+ if (neq(INT_MAX, INT_MIN) != 0) abort();
+ if (nne(INT_MIN, INT_MAX) != -1) abort();
+ if (nne(INT_MAX, INT_MIN) != -1) abort();
+
+ if (ngeu(0, ~0U) != 0) abort();
+ if (ngeu(~0U, 0) != -1) abort();
+ if (ngtu(0, ~0U) != 0) abort();
+ if (ngtu(~0U, 0) != -1) abort();
+ if (nleu(0, ~0U) != -1) abort();
+ if (nleu(~0U, 0) != 0) abort();
+ if (nltu(0, ~0U) != -1) abort();
+ if (nltu(~0U, 0) != 0) abort();
+
+ exit(0);
+ }