commit fc672b6a8b48195b7afaba6f0f9d64e579b1dc72
author Jessica Del <Jessica.Del@amd.com> Tue Feb 21 09:40:07 2023 +0100
committer Jessica Del <Jessica.Del@amd.com> Wed Feb 22 16:39:06 2023 +0100
tree a8a18597a16092aca7ec27b13a9fec53270516cf
parent 7d9d855a073a496540d4e40e67945b6f09d3aea7

[AMDGPU] Improved wide multiplies

These checks show optimized instructions if an operand is known to be
(partially) zero.

Change-Id: Ie2f6d0d3ee9d5b279d1f4c1dd0787492e39cc77a

Differential Revision: https://reviews.llvm.org/D140208

llvm/lib/CodeGen/GlobalISel/Legalizer.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp b/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
index 1a13f39..ee6aaa1 100644
--- a/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/Legalizer.cpp
@@ -18,6 +18,7 @@
 #include "llvm/CodeGen/GlobalISel/CSEInfo.h"
 #include "llvm/CodeGen/GlobalISel/CSEMIRBuilder.h"
 #include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
+#include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"
 #include "llvm/CodeGen/GlobalISel/GISelWorkList.h"
 #include "llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h"
 #include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
@@ -75,6 +76,7 @@
                       false)
 INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
 INITIALIZE_PASS_DEPENDENCY(GISelCSEAnalysisWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(GISelKnownBitsAnalysis)
 INITIALIZE_PASS_END(Legalizer, DEBUG_TYPE,
                     "Legalize the Machine IR a function's Machine IR", false,
                     false)
@@ -85,6 +87,8 @@
   AU.addRequired<TargetPassConfig>();
   AU.addRequired<GISelCSEAnalysisWrapperPass>();
   AU.addPreserved<GISelCSEAnalysisWrapperPass>();
+  AU.addRequired<GISelKnownBitsAnalysis>();
+  AU.addPreserved<GISelKnownBitsAnalysis>();
   getSelectionDAGFallbackAnalysisUsage(AU);
   MachineFunctionPass::getAnalysisUsage(AU);
 }
@@ -173,7 +177,8 @@
 Legalizer::legalizeMachineFunction(MachineFunction &MF, const LegalizerInfo &LI,
                                    ArrayRef<GISelChangeObserver *> AuxObservers,
                                    LostDebugLocObserver &LocObserver,
-                                   MachineIRBuilder &MIRBuilder) {
+                                   MachineIRBuilder &MIRBuilder,
+                                   GISelKnownBits *KB) {
   MIRBuilder.setMF(MF);
   MachineRegisterInfo &MRI = MF.getRegInfo();
 
@@ -212,7 +217,7 @@
   // Now install the observer as the delegate to MF.
   // This will keep all the observers notified about new insertions/deletions.
   RAIIMFObsDelInstaller Installer(MF, WrapperObserver);
-  LegalizerHelper Helper(MF, LI, WrapperObserver, MIRBuilder);
+  LegalizerHelper Helper(MF, LI, WrapperObserver, MIRBuilder, KB);
   LegalizationArtifactCombiner ArtCombiner(MIRBuilder, MRI, LI);
   bool Changed = false;
   SmallVector<MachineInstr *, 128> RetryList;
@@ -338,9 +343,12 @@
   if (VerifyDebugLocs > DebugLocVerifyLevel::None)
     AuxObservers.push_back(&LocObserver);
 
+  // This allows Known Bits Analysis in the legalizer.
+  GISelKnownBits *KB = &getAnalysis<GISelKnownBitsAnalysis>().get(MF);
+
   const LegalizerInfo &LI = *MF.getSubtarget().getLegalizerInfo();
-  MFResult Result =
-      legalizeMachineFunction(MF, LI, AuxObservers, LocObserver, *MIRBuilder);
+  MFResult Result = legalizeMachineFunction(MF, LI, AuxObservers, LocObserver,
+                                            *MIRBuilder, KB);
 
   if (Result.FailedOn) {
     reportGISelFailure(MF, TPC, MORE, "gisel-legalize",

llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 6d579c5..7aa868ab 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -15,6 +15,7 @@
 #include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
 #include "llvm/CodeGen/GlobalISel/CallLowering.h"
 #include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
+#include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"
 #include "llvm/CodeGen/GlobalISel/GenericMachineInstrs.h"
 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
 #include "llvm/CodeGen/GlobalISel/LostDebugLocObserver.h"
@@ -103,13 +104,13 @@
                                  MachineIRBuilder &Builder)
     : MIRBuilder(Builder), Observer(Observer), MRI(MF.getRegInfo()),
       LI(*MF.getSubtarget().getLegalizerInfo()),
-      TLI(*MF.getSubtarget().getTargetLowering()) { }
+      TLI(*MF.getSubtarget().getTargetLowering()), KB(nullptr) {}
 
 LegalizerHelper::LegalizerHelper(MachineFunction &MF, const LegalizerInfo &LI,
                                  GISelChangeObserver &Observer,
-                                 MachineIRBuilder &B)
-  : MIRBuilder(B), Observer(Observer), MRI(MF.getRegInfo()), LI(LI),
-    TLI(*MF.getSubtarget().getTargetLowering()) { }
+                                 MachineIRBuilder &B, GISelKnownBits *KB)
+    : MIRBuilder(B), Observer(Observer), MRI(MF.getRegInfo()), LI(LI),
+      TLI(*MF.getSubtarget().getTargetLowering()), KB(KB) {}
 
 LegalizerHelper::LegalizeResult
 LegalizerHelper::legalizeInstrStep(MachineInstr &MI,