[llvm] 765b37a - [AArch64][GlobalISel] Fallback if the +strict-align target feature is given.

[Amara Emerson via llvm-commits]

Author: Amara Emerson
Date: 2020-01-23T14:45:29-08:00
New Revision: 765b37abdfc037746bf51c43bcb1b8785b6639f0

URL: https://github.com/llvm/llvm-project/commit/765b37abdfc037746bf51c43bcb1b8785b6639f0
DIFF: https://github.com/llvm/llvm-project/commit/765b37abdfc037746bf51c43bcb1b8785b6639f0.diff

LOG: [AArch64][GlobalISel] Fallback if the +strict-align target feature is given.

Works around PR44246.

Added: 
    

Modified: 
    llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
    llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll

Removed: 
    


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diff  --git a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
index 500e1196148d..30fdd55e7473 100644
--- a/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstructionSelector.cpp
@@ -1423,6 +1423,14 @@ bool AArch64InstructionSelector::select(MachineInstr &I) {
   MachineFunction &MF = *MBB.getParent();
   MachineRegisterInfo &MRI = MF.getRegInfo();
 
+  const AArch64Subtarget *Subtarget =
+      &static_cast<const AArch64Subtarget &>(MF.getSubtarget());
+  if (Subtarget->requiresStrictAlign()) {
+    // We don't support this feature yet.
+    LLVM_DEBUG(dbgs() << "AArch64 GISel does not support strict-align yet\n");
+    return false;
+  }
+
   unsigned Opcode = I.getOpcode();
   // G_PHI requires same handling as PHI
   if (!isPreISelGenericOpcode(Opcode) || Opcode == TargetOpcode::G_PHI) {

diff  --git a/llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll b/llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
index 78ae99d98444..6aaa9ab0d11b 100644
--- a/llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
+++ b/llvm/test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
@@ -209,3 +209,12 @@ define <4 x i16> @zext_v4s8(<4 x i8> %in) {
   ret <4 x i16> %ext
 }
 
+; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: cannot select: RET_ReallyLR implicit $x0 (in function: strict_align_feature)
+; FALLBACK-WITH-REPORT-ERR: warning: Instruction selection used fallback path for strict_align_feature
+; FALLBACK-WITH-REPORT-OUT-LABEL: strict_align_feature
+define i64 @strict_align_feature(i64* %p) #0 {
+  %x = load i64, i64* %p, align 1
+  ret i64 %x
+}
+
+attributes #0 = { "target-features"="+strict-align" }