diff options
| -rw-r--r-- | src/passes/OptimizeInstructions.cpp | 22 | ||||
| -rw-r--r-- | test/passes/optimize-instructions_fuzz-exec.txt | 37 | ||||
| -rw-r--r-- | test/passes/optimize-instructions_fuzz-exec.wast | 25 |
3 files changed, 71 insertions, 13 deletions
diff --git a/src/passes/OptimizeInstructions.cpp b/src/passes/OptimizeInstructions.cpp index 2ca670f89..2b0a95fc7 100644 --- a/src/passes/OptimizeInstructions.cpp +++ b/src/passes/OptimizeInstructions.cpp @@ -468,9 +468,9 @@ struct OptimizeInstructions if (auto* binary = curr->dynCast<Binary>()) { if (auto* ext = Properties::getAlmostSignExt(binary)) { - Index extraShifts; - auto bits = Properties::getAlmostSignExtBits(binary, extraShifts); - if (extraShifts == 0) { + Index extraLeftShifts; + auto bits = Properties::getAlmostSignExtBits(binary, extraLeftShifts); + if (extraLeftShifts == 0) { if (auto* load = Properties::getFallthrough(ext, getPassOptions(), features) ->dynCast<Load>()) { @@ -488,11 +488,17 @@ struct OptimizeInstructions } } } - // if the sign-extend input cannot have a sign bit, we don't need it - // we also don't need it if it already has an identical-sized sign - // extend - if (Bits::getMaxBits(ext, this) + extraShifts < bits || - isSignExted(ext, bits)) { + // We can in some cases remove part of a sign extend, that is, + // (x << A) >> B => x << (A - B) + // If the sign-extend input cannot have a sign bit, we don't need it. + if (Bits::getMaxBits(ext, this) + extraLeftShifts < bits) { + return removeAlmostSignExt(binary); + } + // We also don't need it if it already has an identical-sized sign + // extend applied to it. That is, if it is already a sign-extended + // value, then another sign extend will do nothing. We do need to be + // careful of the extra shifts, though. + if (isSignExted(ext, bits) && extraLeftShifts == 0) { return removeAlmostSignExt(binary); } } else if (binary->op == EqInt32 || binary->op == NeInt32) { diff --git a/test/passes/optimize-instructions_fuzz-exec.txt b/test/passes/optimize-instructions_fuzz-exec.txt index e8985222d..27d8795ed 100644 --- a/test/passes/optimize-instructions_fuzz-exec.txt +++ b/test/passes/optimize-instructions_fuzz-exec.txt @@ -257,19 +257,22 @@ [LoggingExternalInterface logging 1] [LoggingExternalInterface logging 1] [LoggingExternalInterface logging 0] +[fuzz-exec] calling do-shift +[LoggingExternalInterface logging -64] [fuzz-exec] calling call-compare-maybe-signed-eq [fuzz-exec] note result: call-compare-maybe-signed-eq => 0 [fuzz-exec] calling call-compare-maybe-signed-ne [fuzz-exec] note result: call-compare-maybe-signed-ne => 1 (module (type $i32_=>_none (func (param i32))) + (type $none_=>_none (func)) (type $none_=>_i32 (func (result i32))) (type $i32_=>_i32 (func (param i32) (result i32))) - (type $none_=>_none (func)) (import "fuzzing-support" "log-i32" (func $log (param i32))) (export "foo" (func $1)) - (export "call-compare-maybe-signed-eq" (func $3)) - (export "call-compare-maybe-signed-ne" (func $5)) + (export "do-shift" (func $3)) + (export "call-compare-maybe-signed-eq" (func $5)) + (export "call-compare-maybe-signed-ne" (func $7)) (func $signed-comparison-to-unsigned (call $log (block (result i32) @@ -321,13 +324,35 @@ ) ) ) + (func $shift (param $0 i32) + (call $log + (i32.shr_s + (i32.shl + (i32.shr_s + (i32.shl + (local.get $0) + (i32.const 24) + ) + (i32.const 24) + ) + (i32.const 30) + ) + (i32.const 24) + ) + ) + ) + (func $3 + (call $shift + (i32.const 65419) + ) + ) (func $compare-maybe-signed-eq (param $0 i32) (result i32) (drop (local.get $0) ) (i32.const 0) ) - (func $3 (result i32) + (func $5 (result i32) (call $compare-maybe-signed-eq (i32.const 128) ) @@ -338,7 +363,7 @@ ) (i32.const 1) ) - (func $5 (result i32) + (func $7 (result i32) (call $compare-maybe-signed-ne (i32.const 128) ) @@ -348,6 +373,8 @@ [LoggingExternalInterface logging 1] [LoggingExternalInterface logging 1] [LoggingExternalInterface logging 0] +[fuzz-exec] calling do-shift +[LoggingExternalInterface logging -64] [fuzz-exec] calling call-compare-maybe-signed-eq [fuzz-exec] note result: call-compare-maybe-signed-eq => 0 [fuzz-exec] calling call-compare-maybe-signed-ne diff --git a/test/passes/optimize-instructions_fuzz-exec.wast b/test/passes/optimize-instructions_fuzz-exec.wast index 8bd43b694..87b6eb594 100644 --- a/test/passes/optimize-instructions_fuzz-exec.wast +++ b/test/passes/optimize-instructions_fuzz-exec.wast @@ -287,6 +287,31 @@ ) ) ) + (func $shift (param $0 i32) + (call $log + ;; x << 24 >> 24 << 30 >> 24 - the extra shifts make it invalid to do the + ;; optimization of not repeating a sign-extend. That is, this would be valid + ;; if the 30 were replaced by a 24. + (i32.shr_s + (i32.shl + (i32.shr_s + (i32.shl + (local.get $0) + (i32.const 24) + ) + (i32.const 24) + ) + (i32.const 30) + ) + (i32.const 24) + ) + ) + ) + (func "do-shift" + (call $shift + (i32.const 65419) + ) + ) ;; similar, but with the value compared to having the sign bit set but no ;; upper bits (func $compare-maybe-signed-eq (param $0 i32) (result i32) |