[llvm] r328346 - [Hexagon] Always generate mux out of predicated transfers if possible
Krzysztof Parzyszek via llvm-commits
llvm-commits at lists.llvm.org
Fri Mar 23 11:43:09 PDT 2018
Author: kparzysz
Date: Fri Mar 23 11:43:09 2018
New Revision: 328346
URL: http://llvm.org/viewvc/llvm-project?rev=328346&view=rev
Log:
[Hexagon] Always generate mux out of predicated transfers if possible
HexagonGenMux would collapse pairs of predicated transfers if it assumed
that the predicated .new forms cannot be created. Turns out that generating
mux is preferable in almost all cases.
Introduce an option -hexagon-gen-mux-threshold that controls the minimum
distance between the instruction defining the predicate and the later of
the two transfers. If the distance is closer than the threshold, mux will
not be generated. Set the threshold to 0 by default.
Added:
llvm/trunk/test/CodeGen/Hexagon/formal-args-i1.ll
llvm/trunk/test/CodeGen/Hexagon/optimize-mux.ll
llvm/trunk/test/CodeGen/Hexagon/split-muxii.ll
Modified:
llvm/trunk/lib/Target/Hexagon/HexagonGenMux.cpp
llvm/trunk/test/CodeGen/Hexagon/cmp_pred.ll
llvm/trunk/test/CodeGen/Hexagon/cmp_pred_reg.ll
llvm/trunk/test/CodeGen/Hexagon/cmpb_pred.ll
llvm/trunk/test/MC/Hexagon/inst_select.ll
Modified: llvm/trunk/lib/Target/Hexagon/HexagonGenMux.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Hexagon/HexagonGenMux.cpp?rev=328346&r1=328345&r2=328346&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Hexagon/HexagonGenMux.cpp (original)
+++ llvm/trunk/lib/Target/Hexagon/HexagonGenMux.cpp Fri Mar 23 11:43:09 2018
@@ -40,6 +40,7 @@
#include "llvm/MC/MCInstrDesc.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Pass.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <cassert>
@@ -56,6 +57,11 @@ namespace llvm {
} // end namespace llvm
+// Initialize this to 0 to always prefer generating mux by default.
+static cl::opt<unsigned> MinPredDist("hexagon-gen-mux-threshold", cl::Hidden,
+ cl::init(0), cl::desc("Minimum distance between predicate definition and "
+ "farther of the two predicated uses"));
+
namespace {
class HexagonGenMux : public MachineFunctionPass {
@@ -269,11 +275,13 @@ bool HexagonGenMux::genMuxInBlock(Machin
// There is now a complete definition of DR, i.e. we have the predicate
// register, the definition if-true, and definition if-false.
- // First, check if both definitions are far enough from the definition
+ // First, check if the definitions are far enough from the definition
// of the predicate register.
unsigned MinX = std::min(CI.TrueX, CI.FalseX);
unsigned MaxX = std::max(CI.TrueX, CI.FalseX);
- unsigned SearchX = (MaxX > 4) ? MaxX-4 : 0;
+ // Specifically, check if the predicate definition is within a prescribed
+ // distance from the farther of the two predicated instructions.
+ unsigned SearchX = (MaxX >= MinPredDist) ? MaxX-MinPredDist : 0;
bool NearDef = false;
for (unsigned X = SearchX; X < MaxX; ++X) {
const DefUseInfo &DU = DUM.lookup(X);
Modified: llvm/trunk/test/CodeGen/Hexagon/cmp_pred.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/cmp_pred.ll?rev=328346&r1=328345&r2=328346&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/cmp_pred.ll (original)
+++ llvm/trunk/test/CodeGen/Hexagon/cmp_pred.ll Fri Mar 23 11:43:09 2018
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -mcpu=hexagonv5 < %s | FileCheck %s
+; RUN: llc -march=hexagon -hexagon-gen-mux-threshold=4 < %s | FileCheck %s
; Generate various cmpb instruction followed by if (p0) .. if (!p0)...
target triple = "hexagon"
Modified: llvm/trunk/test/CodeGen/Hexagon/cmp_pred_reg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/cmp_pred_reg.ll?rev=328346&r1=328345&r2=328346&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/cmp_pred_reg.ll (original)
+++ llvm/trunk/test/CodeGen/Hexagon/cmp_pred_reg.ll Fri Mar 23 11:43:09 2018
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -mcpu=hexagonv5 < %s | FileCheck %s
+; RUN: llc -march=hexagon -hexagon-gen-mux-threshold=4 < %s | FileCheck %s
; Generate various cmpb instruction followed by if (p0) .. if (!p0)...
target triple = "hexagon"
Modified: llvm/trunk/test/CodeGen/Hexagon/cmpb_pred.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/cmpb_pred.ll?rev=328346&r1=328345&r2=328346&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/cmpb_pred.ll (original)
+++ llvm/trunk/test/CodeGen/Hexagon/cmpb_pred.ll Fri Mar 23 11:43:09 2018
@@ -1,4 +1,4 @@
-; RUN: llc -march=hexagon -mcpu=hexagonv5 < %s | FileCheck %s
+; RUN: llc -march=hexagon -hexagon-gen-mux-threshold=4 < %s | FileCheck %s
; Generate various cmpb instruction followed by if (p0) .. if (!p0)...
target triple = "hexagon"
Added: llvm/trunk/test/CodeGen/Hexagon/formal-args-i1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/formal-args-i1.ll?rev=328346&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/formal-args-i1.ll (added)
+++ llvm/trunk/test/CodeGen/Hexagon/formal-args-i1.ll Fri Mar 23 11:43:09 2018
@@ -0,0 +1,17 @@
+; RUN: llc -march=hexagon < %s | FileCheck %s
+; This tests validates the fact that the formal arguments of type scalar i1
+; (passed using 32-bit register) is converted back to use predicate registers
+; CHECK: [[P0:p[0-3]]] = tstbit(r0,#0)
+; CHECK: [[R0:r[0-9]+]] = mux([[P0]],#3,r2)
+; CHECK: memb(r1+#0) = [[R0]]
+
+target triple = "hexagon"
+
+define void @f0(i1 zeroext %a0, i8* nocapture %a1, i8 %a2) local_unnamed_addr #0 {
+entry:
+ %v0 = select i1 %a0, i8 3, i8 %a2
+ store i8 %v0, i8* %a1, align 1
+ ret void
+}
+
+attributes #0 = { norecurse nounwind optsize "target-cpu"="hexagonv60" }
Added: llvm/trunk/test/CodeGen/Hexagon/optimize-mux.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/optimize-mux.ll?rev=328346&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/optimize-mux.ll (added)
+++ llvm/trunk/test/CodeGen/Hexagon/optimize-mux.ll Fri Mar 23 11:43:09 2018
@@ -0,0 +1,20 @@
+; RUN: llc -march=hexagon -hexagon-gen-mux-threshold=0 < %s | FileCheck %s --check-prefix=CHECK0
+; RUN: llc -march=hexagon -hexagon-gen-mux-threshold=4 < %s | FileCheck %s --check-prefix=CHECK4
+
+; Generate mux with threshold = 0:
+; CHECK0: [[R0:r[0-9]+]] = add(r0,#-48)
+; CHECK0: [[P0:p[0-3]]] = cmpb.gtu([[R0]],#9)
+; CHECK0: r0 = mux([[P0]],#0,#1)
+
+; No mux for threshold = 4:
+; CHECK4-NOT: mux
+
+define zeroext i8 @f0(i8 zeroext %a0) #0 {
+b0:
+ %v0 = add i8 %a0, -48
+ %v1 = icmp ult i8 %v0, 10
+ %v2 = zext i1 %v1 to i8
+ ret i8 %v2
+}
+
+attributes #0 = { nounwind readnone }
Added: llvm/trunk/test/CodeGen/Hexagon/split-muxii.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Hexagon/split-muxii.ll?rev=328346&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/Hexagon/split-muxii.ll (added)
+++ llvm/trunk/test/CodeGen/Hexagon/split-muxii.ll Fri Mar 23 11:43:09 2018
@@ -0,0 +1,24 @@
+; RUN: llc -march=hexagon -O2 -hexagon-expand-condsets=true -hexagon-gen-mux-threshold=4 < %s | FileCheck %s
+; CHECK-NOT: mux(p
+
+target triple = "hexagon"
+
+define void @f0() #0 {
+b0:
+ %v0 = load i32, i32* null, align 4
+ %v1 = icmp slt i32 undef, %v0
+ %v2 = zext i1 %v1 to i32
+ %v3 = icmp sgt i32 undef, 0
+ %v4 = zext i1 %v3 to i32
+ %v5 = add nsw i32 %v2, %v4
+ store i32 %v5, i32* undef, align 4
+ br i1 undef, label %b1, label %b2
+
+b1: ; preds = %b0
+ br label %b2
+
+b2: ; preds = %b1, %b0
+ unreachable
+}
+
+attributes #0 = { nounwind }
Modified: llvm/trunk/test/MC/Hexagon/inst_select.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/Hexagon/inst_select.ll?rev=328346&r1=328345&r2=328346&view=diff
==============================================================================
--- llvm/trunk/test/MC/Hexagon/inst_select.ll (original)
+++ llvm/trunk/test/MC/Hexagon/inst_select.ll Fri Mar 23 11:43:09 2018
@@ -7,7 +7,6 @@ define i32 @foo (i1 %a, i32 %b, i32 %c)
ret i32 %1
}
-; CHECK: 00 40 00 85 85004000 { p0 = tstbit(r0,#0)
-; CHECK: 00 40 9f 52 529f4000 jumpr r31
-; CHECK: 00 60 01 74 74016000 if (p0.new) r0 = add(r1,#0)
-; CHECK: 00 e0 82 74 7482e000 if (!p0.new) r0 = add(r2,#0) }
+; CHECK: 00 c0 00 85 8500c000 { p0 = tstbit(r0,#0) }
+; CHECK: 00 42 01 f4 f4014200 { r0 = mux(p0,r1,r2)
+; CHECK: 00 c0 9f 52 529fc000 jumpr r31 }
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