[llvm] r266203 - [mips] Sign-extend i32 values truncated from previously zero-extended i32 values.
Vasileios Kalintiris via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 13 08:07:45 PDT 2016
Author: vkalintiris
Date: Wed Apr 13 10:07:45 2016
New Revision: 266203
URL: http://llvm.org/viewvc/llvm-project?rev=266203&view=rev
Log:
[mips] Sign-extend i32 values truncated from previously zero-extended i32 values.
Summary:
This is a special case for MIPS64 because the architecture requires
properly 32-bit sign-extended values in the register containers.
Additionaly, we merge consecutive trunc + AssertZExt nodes in order
to avoid unnecessary sign-extensions when the extension comes from a
type smaller than i32.
Reviewers: dsanders
Subscribers: dsanders, sdardis, llvm-commits
Differential Revision: http://reviews.llvm.org/D18893
Added:
llvm/trunk/test/CodeGen/Mips/assertzext-trunc.ll
Modified:
llvm/trunk/lib/Target/Mips/Mips64InstrInfo.td
llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp
llvm/trunk/test/CodeGen/Mips/divrem.ll
llvm/trunk/test/CodeGen/Mips/octeon_popcnt.ll
Modified: llvm/trunk/lib/Target/Mips/Mips64InstrInfo.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/Mips64InstrInfo.td?rev=266203&r1=266202&r2=266203&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/Mips64InstrInfo.td (original)
+++ llvm/trunk/lib/Target/Mips/Mips64InstrInfo.td Wed Apr 13 10:07:45 2016
@@ -63,6 +63,10 @@ def PowerOf2HI : PatLeaf<(imm), [{
return false;
}]>;
+def assertzext_lt_i32 : PatFrag<(ops node:$src), (assertzext node:$src), [{
+ return cast<VTSDNode>(N->getOperand(1))->getVT().bitsLT(MVT::i32);
+}]>;
+
//===----------------------------------------------------------------------===//
// Instructions specific format
//===----------------------------------------------------------------------===//
@@ -511,7 +515,17 @@ defm : SetgeImmPats<GPR64, SLTi64, SLTiu
// truncate
def : MipsPat<(trunc (assertsext GPR64:$src)),
(EXTRACT_SUBREG GPR64:$src, sub_32)>;
-def : MipsPat<(trunc (assertzext GPR64:$src)),
+// The forward compatibility strategy employed by MIPS requires us to treat
+// values as being sign extended to an infinite number of bits. This allows
+// existing software to run without modification on any future MIPS
+// implementation (e.g. 128-bit, or 1024-bit). Being compatible with this
+// strategy requires that truncation acts as a sign-extension for values being
+// fed into instructions operating on 32-bit values. Such instructions have
+// undefined results if this is not true.
+// For our case, this means that we can't issue an extract_subreg for nodes
+// such as (trunc:i32 (assertzext:i64 X, i32)), because the sign-bit of the
+// lower subreg would not be replicated into the upper half.
+def : MipsPat<(trunc (assertzext_lt_i32 GPR64:$src)),
(EXTRACT_SUBREG GPR64:$src, sub_32)>;
def : MipsPat<(i32 (trunc GPR64:$src)),
(SLL (EXTRACT_SUBREG GPR64:$src, sub_32), 0)>;
Modified: llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp?rev=266203&r1=266202&r2=266203&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp Wed Apr 13 10:07:45 2016
@@ -428,6 +428,7 @@ MipsTargetLowering::MipsTargetLowering(c
setTargetDAGCombine(ISD::AND);
setTargetDAGCombine(ISD::OR);
setTargetDAGCombine(ISD::ADD);
+ setTargetDAGCombine(ISD::AssertZext);
setMinFunctionAlignment(Subtarget.isGP64bit() ? 3 : 2);
@@ -807,6 +808,37 @@ static SDValue performADDCombine(SDNode
return DAG.getNode(ISD::ADD, DL, ValTy, Add1, Lo);
}
+static SDValue performAssertZextCombine(SDNode *N, SelectionDAG &DAG,
+ TargetLowering::DAGCombinerInfo &DCI,
+ const MipsSubtarget &Subtarget) {
+ SDValue N0 = N->getOperand(0);
+ EVT NarrowerVT = cast<VTSDNode>(N->getOperand(1))->getVT();
+
+ if (N0.getOpcode() != ISD::TRUNCATE)
+ return SDValue();
+
+ if (N0.getOperand(0).getOpcode() != ISD::AssertZext)
+ return SDValue();
+
+ // fold (AssertZext (trunc (AssertZext x))) -> (trunc (AssertZext x))
+ // if the type of the extension of the innermost AssertZext node is
+ // smaller from that of the outermost node, eg:
+ // (AssertZext:i32 (trunc:i32 (AssertZext:i64 X, i32)), i8)
+ // -> (trunc:i32 (AssertZext X, i8))
+ SDValue WiderAssertZext = N0.getOperand(0);
+ EVT WiderVT = cast<VTSDNode>(WiderAssertZext->getOperand(1))->getVT();
+
+ if (NarrowerVT.bitsLT(WiderVT)) {
+ SDValue NewAssertZext = DAG.getNode(
+ ISD::AssertZext, SDLoc(N), WiderAssertZext.getValueType(),
+ WiderAssertZext.getOperand(0), DAG.getValueType(NarrowerVT));
+ return DAG.getNode(ISD::TRUNCATE, SDLoc(N), N->getValueType(0),
+ NewAssertZext);
+ }
+
+ return SDValue();
+}
+
SDValue MipsTargetLowering::PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI)
const {
SelectionDAG &DAG = DCI.DAG;
@@ -828,6 +860,8 @@ SDValue MipsTargetLowering::PerformDAGC
return performORCombine(N, DAG, DCI, Subtarget);
case ISD::ADD:
return performADDCombine(N, DAG, DCI, Subtarget);
+ case ISD::AssertZext:
+ return performAssertZextCombine(N, DAG, DCI, Subtarget);
}
return SDValue();
Added: llvm/trunk/test/CodeGen/Mips/assertzext-trunc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/assertzext-trunc.ll?rev=266203&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/assertzext-trunc.ll (added)
+++ llvm/trunk/test/CodeGen/Mips/assertzext-trunc.ll Wed Apr 13 10:07:45 2016
@@ -0,0 +1,62 @@
+; RUN: llc < %s -march=mips64 -mcpu=mips3 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips4 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips64 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips64r2 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips64r3 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips64r5 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=PRE-R6
+; RUN: llc < %s -march=mips64 -mcpu=mips64r6 | FileCheck %s \
+; RUN: -check-prefix=ALL -check-prefix=R6
+
+; Check that we don't emit redundant SLLs for sequences of
+; (AssertZext:i32 (trunc:i32 (AssertZext:i64 X, i32)), i8)
+define zeroext i8 @udiv_i8(i8 zeroext %a, i8 zeroext %b) {
+entry:
+; ALL-LABEL: udiv_i8:
+
+ ; PRE-R6-NOT: sll {{.*}}
+ ; PRE-R6: divu $zero, $4, $5
+ ; PRE-R6: teq $5, $zero, 7
+ ; PRE-R6: mflo $2
+
+ ; R6-NOT: sll {{.*}}
+ ; R6: divu $2, $4, $5
+ ; R6: teq $5, $zero, 7
+
+ %r = udiv i8 %a, %b
+ ret i8 %r
+}
+
+; Check that we do sign-extend when we have a (trunc:i32 (AssertZext:i64 X, i32))
+define i64 @foo1(i64 zeroext %var) {
+entry:
+; ALL-LABEL: foo1:
+
+ %shr = lshr i64 %var, 32
+ %cmp = icmp eq i64 %shr, 0
+ br i1 %cmp, label %if.end6, label %if.then
+
+ ; ALL: dsrl $[[T0:[0-9]+]], $4, 32
+ ; ALL: sll $[[T1:[0-9]+]], $[[T0]], 0
+ if.then: ; preds = %entry
+ %conv = trunc i64 %shr to i32
+ %cmp2 = icmp slt i32 %conv, 0
+ br i1 %cmp2, label %if.then4, label %if.else
+
+ if.then4: ; preds = %if.then
+ %add = add i64 %var, 16
+ br label %if.end6
+
+ if.else: ; preds = %if.then
+ %add5 = add i64 %var, 32
+ br label %if.end6
+
+ if.end6: ; preds = %entry, %if.then4, %if.else
+ %var.addr.0 = phi i64 [ %add, %if.then4 ], [ %add5, %if.else ], [ %var, %entry ]
+ ret i64 %var.addr.0
+}
Modified: llvm/trunk/test/CodeGen/Mips/divrem.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/divrem.ll?rev=266203&r1=266202&r2=266203&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/divrem.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/divrem.ll Wed Apr 13 10:07:45 2016
@@ -81,7 +81,7 @@ entry:
ret i32 %rem
}
-define i32 @udiv1(i32 zeroext %a0, i32 zeroext %a1) nounwind readnone {
+define i32 @udiv1(i32 signext %a0, i32 signext %a1) nounwind readnone {
entry:
; ALL-LABEL: udiv1:
@@ -107,7 +107,7 @@ entry:
ret i32 %div
}
-define i32 @urem1(i32 zeroext %a0, i32 zeroext %a1) nounwind readnone {
+define i32 @urem1(i32 signext %a0, i32 signext %a1) nounwind readnone {
entry:
; ALL-LABEL: urem1:
@@ -175,7 +175,7 @@ entry:
ret i32 %div
}
-define i32 @udivrem1(i32 zeroext %a0, i32 zeroext %a1, i32* nocapture %r) nounwind {
+define i32 @udivrem1(i32 signext %a0, i32 signext %a1, i32* nocapture %r) nounwind {
entry:
; ALL-LABEL: udivrem1:
Modified: llvm/trunk/test/CodeGen/Mips/octeon_popcnt.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/octeon_popcnt.ll?rev=266203&r1=266202&r2=266203&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/octeon_popcnt.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/octeon_popcnt.ll Wed Apr 13 10:07:45 2016
@@ -21,7 +21,7 @@ define i16 @cnt16(i16 %x) nounwind readn
; MIPS64-NOT: pop
}
-define i32 @cnt32(i32 zeroext %x) nounwind readnone {
+define i32 @cnt32(i32 signext %x) nounwind readnone {
%cnt = tail call i32 @llvm.ctpop.i32(i32 %x)
ret i32 %cnt
; OCTEON-LABEL: cnt32:
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