[X2Go-Commits] [pale-moon] 153/294: Restrict ExtractLinearSum to monotonous operation in infinite math space.

[git-admin at x2go.org]

This is an automated email from the git hooks/post-receive script.

x2go pushed a commit to branch upstream/28.5.0
in repository pale-moon.

commit 357ea8cae97edf53d765406dd74bef157b82aa5c
Author: Nicolas B. Pierron <nicolas.b.pierron at nbp.name>
Date:   Sat Mar 23 09:36:15 2019 +0100

    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.
---
 js/src/jit/IonAnalysis.cpp | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/js/src/jit/IonAnalysis.cpp b/js/src/jit/IonAnalysis.cpp
index b163d58..d255c32 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);
     }
 

--
Alioth's /home/x2go-admin/maintenancescripts/git/hooks/post-receive-email on /srv/git/code.x2go.org/pale-moon.git