From 4cd1b67491df2fc927057feb567db8e418e28d80 Mon Sep 17 00:00:00 2001 From: Noah Goldstein Date: Fri, 28 Apr 2023 01:18:20 -0500 Subject: [PATCH] [ValueTracking] Add logic for `fshl/fshr(A, B, C) != 0` if `A == B && A ! = 0` Having `A == B` is quite common for rotate patterns. Alive2 Links: - https://alive2.llvm.org/ce/z/mPXi9c - https://alive2.llvm.org/ce/z/UfDHoI Reviewed By: nikic Differential Revision: https://reviews.llvm.org/D149372 --- llvm/lib/Analysis/ValueTracking.cpp | 6 ++++++ llvm/test/Analysis/ValueTracking/known-non-zero.ll | 10 ++-------- 2 files changed, 8 insertions(+), 8 deletions(-) diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp index c36bb35..57a6533 100644 --- a/llvm/lib/Analysis/ValueTracking.cpp +++ b/llvm/lib/Analysis/ValueTracking.cpp @@ -2894,6 +2894,12 @@ bool isKnownNonZero(const Value *V, const APInt &DemandedElts, unsigned Depth, isKnownNonZero(II->getArgOperand(1), DemandedElts, Depth, Q)) return true; break; + case Intrinsic::fshr: + case Intrinsic::fshl: + // If Op0 == Op1, this is a rotate. rotate(x, y) != 0 iff x != 0. + if (II->getArgOperand(0) == II->getArgOperand(1)) + return isKnownNonZero(II->getArgOperand(0), DemandedElts, Depth, Q); + break; case Intrinsic::vscale: return true; default: diff --git a/llvm/test/Analysis/ValueTracking/known-non-zero.ll b/llvm/test/Analysis/ValueTracking/known-non-zero.ll index ccb82b2..c6ea1ed 100644 --- a/llvm/test/Analysis/ValueTracking/known-non-zero.ll +++ b/llvm/test/Analysis/ValueTracking/known-non-zero.ll @@ -532,10 +532,7 @@ define i1 @fshr_non_zero(i8 %x, i8 %y, i8 %z) { ; CHECK-LABEL: @fshr_non_zero( ; CHECK-NEXT: [[PRED0:%.*]] = icmp ne i8 [[X:%.*]], 0 ; CHECK-NEXT: call void @llvm.assume(i1 [[PRED0]]) -; CHECK-NEXT: [[V:%.*]] = tail call i8 @llvm.fshr.i8(i8 [[X]], i8 [[X]], i8 [[Y:%.*]]) -; CHECK-NEXT: [[OR:%.*]] = or i8 [[V]], [[Z:%.*]] -; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[OR]], 0 -; CHECK-NEXT: ret i1 [[R]] +; CHECK-NEXT: ret i1 false ; %pred0 = icmp ne i8 %x, 0 call void @llvm.assume(i1 %pred0) @@ -570,10 +567,7 @@ define i1 @fshl_non_zero(i8 %x, i8 %y, i8 %z) { ; CHECK-LABEL: @fshl_non_zero( ; CHECK-NEXT: [[PRED0:%.*]] = icmp ne i8 [[X:%.*]], 0 ; CHECK-NEXT: call void @llvm.assume(i1 [[PRED0]]) -; CHECK-NEXT: [[V:%.*]] = tail call i8 @llvm.fshl.i8(i8 [[X]], i8 [[X]], i8 [[Y:%.*]]) -; CHECK-NEXT: [[OR:%.*]] = or i8 [[V]], [[Z:%.*]] -; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[OR]], 0 -; CHECK-NEXT: ret i1 [[R]] +; CHECK-NEXT: ret i1 false ; %pred0 = icmp ne i8 %x, 0 call void @llvm.assume(i1 %pred0) -- 2.7.4