[llvm] 7432fb2 - [ARM][XO] Execute-only miscompiles double literals for big-endian

[Simon Wallis via llvm-commits]

Author: Simon Wallis
Date: 2020-06-08T08:13:08+01:00
New Revision: 7432fb2c784691eb85b5996e0922b55389b43b6e

URL: https://github.com/llvm/llvm-project/commit/7432fb2c784691eb85b5996e0922b55389b43b6e
DIFF: https://github.com/llvm/llvm-project/commit/7432fb2c784691eb85b5996e0922b55389b43b6e.diff

LOG: [ARM][XO] Execute-only miscompiles double literals for big-endian

Summary:
With -mbig-endian -mexecute-only and targeting an fpu,
an incorrect sequence of movw/movt was generated to construct a double literal.
The test suite was hardwired to check these wrong values.

The fault was caused by the explicit word swap in LowerConstantFP().

With -mbig-endian -mexecute-only -mfpu=none, a correct sequence of
movw/movt is generated to construct a double literal.
The test suite did not test this no fpu case.

The test suite expected values have been corrected.
The test file is updated to add testing of fpu=none case

Reviewers: christof, llvm-commits, dmgreen

Reviewed By: dmgreen

Subscribers: dmgreen, kristof.beyls, hiraditya, danielkiss

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81259

Change-Id: Ia3737df243218c89c82f02b7f9f4032ecd5a3917

Added: 
    

Modified: 
    llvm/lib/Target/ARM/ARMISelLowering.cpp
    llvm/test/CodeGen/ARM/constantfp.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 0bd726ebdcf5..ee8fd6507d28 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -6644,8 +6644,6 @@ SDValue ARMTargetLowering::LowerConstantFP(SDValue Op, SelectionDAG &DAG,
       case MVT::f64: {
         SDValue Lo = DAG.getConstant(INTVal.trunc(32), DL, MVT::i32);
         SDValue Hi = DAG.getConstant(INTVal.lshr(32).trunc(32), DL, MVT::i32);
-        if (!ST->isLittle())
-          std::swap(Lo, Hi);
         return DAG.getNode(ARMISD::VMOVDRR, DL, MVT::f64, Lo, Hi);
       }
       case MVT::f32:

diff  --git a/llvm/test/CodeGen/ARM/constantfp.ll b/llvm/test/CodeGen/ARM/constantfp.ll
index d45d3dcfc1b3..80bf74aa30ff 100644
--- a/llvm/test/CodeGen/ARM/constantfp.ll
+++ b/llvm/test/CodeGen/ARM/constantfp.ll
@@ -9,7 +9,10 @@
 ; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE %s
 
 ; RUN: llc -mtriple=thumbv7meb -mattr=+execute-only -mcpu=cortex-m4 %s -o - \
-; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE %s
+; RUN: | FileCheck --check-prefix=CHECK-XO-FLOAT --check-prefix=CHECK-XO-DOUBLE-BE  --check-prefix=CHECK-XO-DOUBLE-BE-FPREGS %s
+
+; RUN: llc -mtriple=thumbv7meb -mattr=+execute-only -mcpu=cortex-m3 %s -o - \
+; RUN: | FileCheck --check-prefix=CHECK-XO-DOUBLE-BE %s
 
 ; RUN: llc -mtriple=thumbv7m -mattr=+execute-only -mcpu=cortex-m4 -relocation-model=ropi %s -o - \
 ; RUN: | FileCheck --check-prefix=CHECK-XO-ROPI %s
@@ -94,8 +97,8 @@ define arm_aapcs_vfpcc double @test_vmov_double_imm() {
 ; CHECK-XO-DOUBLE-NOT: vldr
 
 ; CHECK-XO-DOUBLE-BE-LABEL: test_vmov_double_imm:
-; CHECK-XO-DOUBLE-BE: movs [[REG:r[0-9]+]], #0
-; CHECK-XO-DOUBLE-BE: vmov {{d[0-9]+}}, [[REG]], [[REG]]
+; CHECK-XO-DOUBLE-BE-FPREGS: movs [[REG:r[0-9]+]], #0
+; CHECK-XO-DOUBLE-BE-FPREGS: vmov {{d[0-9]+}}, [[REG]], [[REG]]
 ; CHECK-XO-DOUBLE-NOT: vldr
   ret double 0.0
 }
@@ -116,8 +119,8 @@ define arm_aapcs_vfpcc double @test_vmvn_double_imm() {
 ; CHECK-XO-DOUBLE-NOT: vldr
 
 ; CHECK-XO-DOUBLE-BE-LABEL: test_vmvn_double_imm:
-; CHECK-XO-DOUBLE-BE: mvn [[REG:r[0-9]+]], #-1342177280
-; CHECK-XO-DOUBLE-BE: vmov {{d[0-9]+}}, [[REG]], [[REG]]
+; CHECK-XO-DOUBLE-BE-FPREGS: mvn [[REG:r[0-9]+]], #-1342177280
+; CHECK-XO-DOUBLE-BE-FPREGS: vmov {{d[0-9]+}}, [[REG]], [[REG]]
 ; CHECK-XO-DOUBLE-BE-NOT: vldr
   ret double 0x4fffffff4fffffff
 }
@@ -141,9 +144,9 @@ define arm_aapcs_vfpcc double @test_notvmvn_double_imm() {
 ; CHECK-XO-DOUBLE-NOT: vldr
 
 ; CHECK-XO-DOUBLE-BE-LABEL: test_notvmvn_double_imm:
-; CHECK-XO-DOUBLE-BE: mov.w [[REG1:r[0-9]+]], #-1
-; CHECK-XO-DOUBLE-BE: mvn [[REG2:r[0-9]+]], #-1342177280
-; CHECK-XO-DOUBLE-BE: vmov {{d[0-9]+}}, [[REG2]], [[REG1]]
+; CHECK-XO-DOUBLE-BE: mvn [[REG1:r[0-9]+]], #-1342177280
+; CHECK-XO-DOUBLE-BE: mov.w [[REG2:r[0-9]+]], #-1
+; CHECK-XO-DOUBLE-BE-FPREGS: vmov {{d[0-9]+}}, [[REG2]], [[REG1]]
 ; CHECK-XO-DOUBLE-BE-NOT: vldr
   ret double 0x4fffffffffffffff
 }
@@ -173,11 +176,11 @@ define arm_aapcs_vfpcc double @lower_const_f64_xo() {
 ; CHECK-XO-DOUBLE-NOT: vldr
 
 ; CHECK-XO-DOUBLE-BE-LABEL: lower_const_f64_xo
-; CHECK-XO-DOUBLE-BE: movw [[REG1:r[0-9]+]], #27263
-; CHECK-XO-DOUBLE-BE: movw [[REG2:r[0-9]+]], #6291
-; CHECK-XO-DOUBLE-BE: movt [[REG1]], #29884
-; CHECK-XO-DOUBLE-BE: movt [[REG2]], #16340
-; CHECK-XO-DOUBLE-BE: vmov {{d[0-9]+}}, [[REG2]], [[REG1]]
+; CHECK-XO-DOUBLE-BE: movw [[REG1:r[0-9]+]], #6291
+; CHECK-XO-DOUBLE-BE: movw [[REG2:r[0-9]+]], #27263
+; CHECK-XO-DOUBLE-BE: movt [[REG1]], #16340
+; CHECK-XO-DOUBLE-BE: movt [[REG2]], #29884
+; CHECK-XO-DOUBLE-BE-FPREGS: vmov {{d[0-9]+}}, [[REG2]], [[REG1]]
 ; CHECK-XO-DOUBLE-BE-NOT: vldr
   ret double 3.140000e-01
 }