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authorNicolas B. Pierron <nicolas.b.pierron@nbp.name>2019-03-23 09:36:15 +0100
committerwolfbeast <mcwerewolf@wolfbeast.com>2019-03-23 09:58:57 +0100
commit054794f8c5c93f502318a99517cfacfd757510d6 (patch)
tree5e2b00f7a313034963fc9f11f803bd92b9fb20a6
parentf33a272de2175d3b631e2f9acd24f63fcae38d2b (diff)
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Restrict ExtractLinearSum to monotonous operation in infinite math space.
Thanks to Bruno Keith & Niklas Baumstark from the phoenhex team for finding this issue and reporting it with a proper analysis.
-rw-r--r--js/src/jit/IonAnalysis.cpp21
1 files changed, 17 insertions, 4 deletions
diff --git a/js/src/jit/IonAnalysis.cpp b/js/src/jit/IonAnalysis.cpp
index b163d5818..d255c32a8 100644
--- a/js/src/jit/IonAnalysis.cpp
+++ b/js/src/jit/IonAnalysis.cpp
@@ -3127,6 +3127,15 @@ ExtractMathSpace(MDefinition* ins)
MOZ_MAKE_COMPILER_ASSUME_IS_UNREACHABLE("Unknown TruncateKind");
}
+static bool MonotoneAdd(int32_t lhs, int32_t rhs) {
+ return (lhs >= 0 && rhs >= 0) || (lhs <= 0 && rhs <= 0);
+}
+
+static bool MonotoneSub(int32_t lhs, int32_t rhs) {
+ return (lhs >= 0 && rhs <= 0) || (lhs <= 0 && rhs >= 0);
+}
+
+
// Extract a linear sum from ins, if possible (otherwise giving the sum 'ins + 0').
SimpleLinearSum
jit::ExtractLinearSum(MDefinition* ins, MathSpace space)
@@ -3168,10 +3177,12 @@ jit::ExtractLinearSum(MDefinition* ins, MathSpace space)
// Check if this is of the form <SUM> + n or n + <SUM>.
if (ins->isAdd()) {
int32_t constant;
- if (space == MathSpace::Modulo)
+ if (space == MathSpace::Modulo) {
constant = lsum.constant + rsum.constant;
- else if (!SafeAdd(lsum.constant, rsum.constant, &constant))
+ } else if (!SafeAdd(lsum.constant, rsum.constant, &constant) ||
+ !MonotoneAdd(lsum.constant, rsum.constant)) {
return SimpleLinearSum(ins, 0);
+ }
return SimpleLinearSum(lsum.term ? lsum.term : rsum.term, constant);
}
@@ -3179,10 +3190,12 @@ jit::ExtractLinearSum(MDefinition* ins, MathSpace space)
// Check if this is of the form <SUM> - n.
if (lsum.term) {
int32_t constant;
- if (space == MathSpace::Modulo)
+ if (space == MathSpace::Modulo) {
constant = lsum.constant - rsum.constant;
- else if (!SafeSub(lsum.constant, rsum.constant, &constant))
+ } else if (!SafeSub(lsum.constant, rsum.constant, &constant) ||
+ !MonotoneSub(lsum.constant, rsum.constant)) {
return SimpleLinearSum(ins, 0);
+ }
return SimpleLinearSum(lsum.term, constant);
}