From 11b1a4ae366d4e7420932284ea806acc3713bc99 Mon Sep 17 00:00:00 2001
From: Ahmed Bougacha <ahmed.bougacha@gmail.com>
Date: Mon, 23 Jan 2017 21:10:14 +0000
Subject: [PATCH] [AArch64][GlobalISel] Legalize narrow scalar fp->int
 conversions.

Since we're now avoiding operations using narrow scalar integer types,
we have to legalize the integer side of the FP conversions.

This requires teaching the legalizer how to do that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292828 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/GlobalISel/LegalizerHelper.cpp         | 14 ++++++++++++++
 lib/Target/AArch64/AArch64LegalizerInfo.cpp        |  5 ++---
 test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir | 18 ++++++++++++------
 3 files changed, 28 insertions(+), 9 deletions(-)

diff --git a/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index f77d807a69d..6da02646250 100644
--- a/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -273,6 +273,20 @@ LegalizerHelper::widenScalar(MachineInstr &MI, unsigned TypeIdx, LLT WideTy) {
     MI.eraseFromParent();
     return Legalized;
   }
+  case TargetOpcode::G_FPTOSI:
+  case TargetOpcode::G_FPTOUI: {
+    if (TypeIdx != 0)
+      return UnableToLegalize;
+
+    unsigned DstExt = MRI.createGenericVirtualRegister(WideTy);
+    MIRBuilder.buildInstr(MI.getOpcode())
+        .addDef(DstExt)
+        .addUse(MI.getOperand(1).getReg());
+
+    MIRBuilder.buildTrunc(MI.getOperand(0).getReg(), DstExt);
+    MI.eraseFromParent();
+    return Legalized;
+  }
   case TargetOpcode::G_SITOFP:
   case TargetOpcode::G_UITOFP: {
     if (TypeIdx != 1)
diff --git a/lib/Target/AArch64/AArch64LegalizerInfo.cpp b/lib/Target/AArch64/AArch64LegalizerInfo.cpp
index 985260700e3..871556c8ed9 100644
--- a/lib/Target/AArch64/AArch64LegalizerInfo.cpp
+++ b/lib/Target/AArch64/AArch64LegalizerInfo.cpp
@@ -151,9 +151,8 @@ AArch64LegalizerInfo::AArch64LegalizerInfo() {
     setAction({G_UITOFP, 1, Ty}, Legal);
   }
   for (auto Ty : { s1, s8, s16 }) {
-    // FIXME: These should be widened on types smaller than s32.
-    setAction({G_FPTOSI, 0, Ty}, Legal);
-    setAction({G_FPTOUI, 0, Ty}, Legal);
+    setAction({G_FPTOSI, 0, Ty}, WidenScalar);
+    setAction({G_FPTOUI, 0, Ty}, WidenScalar);
     setAction({G_SITOFP, 1, Ty}, WidenScalar);
     setAction({G_UITOFP, 1, Ty}, WidenScalar);
   }
diff --git a/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir b/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir
index 968256c7424..8d0af0dc447 100644
--- a/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir
+++ b/test/CodeGen/AArch64/GlobalISel/legalize-fptoi.mir
@@ -130,7 +130,8 @@ body: |
     %0:_(s32) = COPY %w0
 
     ; CHECK-LABEL: name: test_fptosi_s1_s32
-    ; CHECK: %1(s1) = G_FPTOSI %0
+    ; CHECK: %2(s32) = G_FPTOSI %0
+    ; CHECK: %1(s1) = G_TRUNC %2
     %1:_(s1) = G_FPTOSI %0
 ...
 
@@ -142,7 +143,8 @@ body: |
     %0:_(s32) = COPY %w0
 
     ; CHECK-LABEL: name: test_fptoui_s1_s32
-    ; CHECK: %1(s1) = G_FPTOUI %0
+    ; CHECK: %2(s32) = G_FPTOUI %0
+    ; CHECK: %1(s1) = G_TRUNC %2
     %1:_(s1) = G_FPTOUI %0
 ...
 
@@ -154,7 +156,8 @@ body: |
     %0:_(s64) = COPY %x0
 
     ; CHECK-LABEL: name: test_fptosi_s8_s64
-    ; CHECK: %1(s8) = G_FPTOSI %0
+    ; CHECK: %2(s32) = G_FPTOSI %0
+    ; CHECK: %1(s8) = G_TRUNC %2
     %1:_(s8) = G_FPTOSI %0
 ...
 
@@ -166,7 +169,8 @@ body: |
     %0:_(s64) = COPY %x0
 
     ; CHECK-LABEL: name: test_fptoui_s8_s64
-    ; CHECK: %1(s8) = G_FPTOUI %0
+    ; CHECK: %2(s32) = G_FPTOUI %0
+    ; CHECK: %1(s8) = G_TRUNC %2
     %1:_(s8) = G_FPTOUI %0
 ...
 
@@ -178,7 +182,8 @@ body: |
     %0:_(s32) = COPY %w0
 
     ; CHECK-LABEL: name: test_fptosi_s16_s32
-    ; CHECK: %1(s16) = G_FPTOSI %0
+    ; CHECK: %2(s32) = G_FPTOSI %0
+    ; CHECK: %1(s16) = G_TRUNC %2
     %1:_(s16) = G_FPTOSI %0
 ...
 
@@ -190,6 +195,7 @@ body: |
     %0:_(s32) = COPY %w0
 
     ; CHECK-LABEL: name: test_fptoui_s16_s32
-    ; CHECK: %1(s16) = G_FPTOUI %0
+    ; CHECK: %2(s32) = G_FPTOUI %0
+    ; CHECK: %1(s16) = G_TRUNC %2
     %1:_(s16) = G_FPTOUI %0
 ...
-- 
2.11.0