From 1de12041904d5571ead6e64b5e51a3e26c8cfce1 Mon Sep 17 00:00:00 2001 From: Alon Zakai Date: Fri, 28 Jul 2017 14:10:25 -0700 Subject: fix shift computation in getMaxBits - in wasm only the lower 5 bits matter for a 32-bit shift --- src/passes/OptimizeInstructions.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src') diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp index 2930fe9c9..43a8faa32 100644 --- a/src/passes/OptimizeInstructions.cpp +++ b/src/passes/OptimizeInstructions.cpp @@ -195,7 +195,7 @@ Index getMaxBits(Expression* curr, LocalInfoProvider* localInfoProvider) { case ShrUInt32: { if (auto* shift = binary->right->dynCast()) { auto maxBits = getMaxBits(binary->left, localInfoProvider); - auto shifts = std::min(Index(shift->value.geti32()), maxBits); // can ignore more shifts than zero us out + auto shifts = std::min(Index(shift->value.geti32() & 31), maxBits); // can ignore more shifts than zero us out return std::max(Index(0), maxBits - shifts); } return 32; @@ -204,7 +204,7 @@ Index getMaxBits(Expression* curr, LocalInfoProvider* localInfoProvider) { if (auto* shift = binary->right->dynCast()) { auto maxBits = getMaxBits(binary->left, localInfoProvider); if (maxBits == 32) return 32; - auto shifts = std::min(Index(shift->value.geti32()), maxBits); // can ignore more shifts than zero us out + auto shifts = std::min(Index(shift->value.geti32() & 31), maxBits); // can ignore more shifts than zero us out return std::max(Index(0), maxBits - shifts); } return 32; -- cgit v1.2.3