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| author | Richard Kenner <kenner@gcc.gnu.org> | 1993-04-03 17:34:45 -0500 |
|---|---|---|
| committer | Richard Kenner <kenner@gcc.gnu.org> | 1993-04-03 17:34:45 -0500 |
| commit | 20fdd649e587eb923e447773a73c6e3a71d16a64 (patch) | |
| tree | ba73190a046df8b0a6e8b6ac48a9871970c520c5 | |
| parent | be7ae2a48490fa9809c604c6e33e645fc5076f5a (diff) | |
| download | gcc-20fdd649e587eb923e447773a73c6e3a71d16a64.zip gcc-20fdd649e587eb923e447773a73c6e3a71d16a64.tar.gz gcc-20fdd649e587eb923e447773a73c6e3a71d16a64.tar.bz2 | |
(simplify_comparison, case PLUS): Generalize simplification of (eq (plus A B) C).
(simplify_comparison, case PLUS): Generalize simplification
of (eq (plus A B) C).
(simplify_comparison, case MINUS): Add corresponding cases.
From-SVN: r3992
| -rw-r--r-- | gcc/combine.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/gcc/combine.c b/gcc/combine.c index 92fa365..6993356 100644 --- a/gcc/combine.c +++ b/gcc/combine.c @@ -8315,12 +8315,12 @@ simplify_comparison (code, pop0, pop1) break; case PLUS: - /* (eq (plus X C1) C2) -> (eq X (minus C2 C1)). We can only do + /* (eq (plus X A) B) -> (eq X (minus B A)). We can only do this for equality comparisons due to pathological cases involving overflows. */ - if (equality_comparison_p && GET_CODE (XEXP (op0, 1)) == CONST_INT - && (tem = simplify_binary_operation (MINUS, mode, op1, - XEXP (op0, 1))) != 0) + if (equality_comparison_p + && 0 != (tem = simplify_binary_operation (MINUS, mode, + op1, XEXP (op0, 1)))) { op0 = XEXP (op0, 0); op1 = tem; @@ -8338,6 +8338,28 @@ simplify_comparison (code, pop0, pop1) break; case MINUS: + /* (eq (minus A B) C) -> (eq A (plus B C)) or + (eq B (minus A C)), whichever simplifies. We can only do + this for equality comparisons due to pathological cases involving + overflows. */ + if (equality_comparison_p + && 0 != (tem = simplify_binary_operation (PLUS, mode, + XEXP (op0, 1), op1))) + { + op0 = XEXP (op0, 0); + op1 = tem; + continue; + } + + if (equality_comparison_p + && 0 != (tem = simplify_binary_operation (MINUS, mode, + XEXP (op0, 0), op1))) + { + op0 = XEXP (op0, 1); + op1 = tem; + continue; + } + /* The sign bit of (minus (ashiftrt X C) X), where C is the number of bits in X minus 1, is one iff X > 0. */ if (sign_bit_comparison_p && GET_CODE (XEXP (op0, 0)) == ASHIFTRT |