[llvm] a57dd66 - [X86] In X86FastEmitSSESelect, fall back to SelectionDAG if the inputs to the compare can't be found in registers.

[Craig Topper via llvm-commits]

Author: Craig Topper
Date: 2020-02-01T12:24:55-08:00
New Revision: a57dd66d5e1c7e2514d42afdcb74566b76552e60

URL: https://github.com/llvm/llvm-project/commit/a57dd66d5e1c7e2514d42afdcb74566b76552e60
DIFF: https://github.com/llvm/llvm-project/commit/a57dd66d5e1c7e2514d42afdcb74566b76552e60.diff

LOG: [X86] In X86FastEmitSSESelect, fall back to SelectionDAG if the inputs to the compare can't be found in registers.

We were checking that the original Value * for the compare operands
were null. But that can never happen.

I believe we intended to check for 0 registers here instead.

Fixes PR44749.

Added: 
    llvm/test/CodeGen/X86/pr44749.ll

Modified: 
    llvm/lib/Target/X86/X86FastISel.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/X86/X86FastISel.cpp b/llvm/lib/Target/X86/X86FastISel.cpp
index 1dbf40683564..a135f100ba04 100644
--- a/llvm/lib/Target/X86/X86FastISel.cpp
+++ b/llvm/lib/Target/X86/X86FastISel.cpp
@@ -2194,7 +2194,7 @@ bool X86FastISel::X86FastEmitSSESelect(MVT RetVT, const Instruction *I) {
   unsigned CmpRHSReg = getRegForValue(CmpRHS);
   bool CmpRHSIsKill = hasTrivialKill(CmpRHS);
 
-  if (!LHSReg || !RHSReg || !CmpLHS || !CmpRHS)
+  if (!LHSReg || !RHSReg || !CmpLHSReg || !CmpRHSReg)
     return false;
 
   const TargetRegisterClass *RC = TLI.getRegClassFor(RetVT);

diff  --git a/llvm/test/CodeGen/X86/pr44749.ll b/llvm/test/CodeGen/X86/pr44749.ll
new file mode 100644
index 000000000000..5702241ff89a
--- /dev/null
+++ b/llvm/test/CodeGen/X86/pr44749.ll
@@ -0,0 +1,56 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-apple-macosx10.15.0 -O0 | FileCheck %s
+
+define i32 @a() {
+; CHECK-LABEL: a:
+; CHECK:       ## %bb.0: ## %entry
+; CHECK-NEXT:    subq $40, %rsp
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
+; CHECK-NEXT:    movsd {{.*#+}} xmm1 = mem[0],zero
+; CHECK-NEXT:    xorl %eax, %eax
+; CHECK-NEXT:    ## kill: def $al killed $al killed $eax
+; CHECK-NEXT:    movsd %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) ## 8-byte Spill
+; CHECK-NEXT:    movsd %xmm1, {{[-0-9]+}}(%r{{[sb]}}p) ## 8-byte Spill
+; CHECK-NEXT:    callq _b
+; CHECK-NEXT:    cvtsi2sd %eax, %xmm0
+; CHECK-NEXT:    movq _calloc@{{.*}}(%rip), %rcx
+; CHECK-NEXT:    subq $-1, %rcx
+; CHECK-NEXT:    movsd {{.*#+}} xmm1 = mem[0],zero
+; CHECK-NEXT:    xorps %xmm2, %xmm2
+; CHECK-NEXT:    movsd %xmm0, {{[-0-9]+}}(%r{{[sb]}}p) ## 8-byte Spill
+; CHECK-NEXT:    movsd %xmm2, {{[-0-9]+}}(%r{{[sb]}}p) ## 8-byte Spill
+; CHECK-NEXT:    movsd %xmm1, (%rsp) ## 8-byte Spill
+; CHECK-NEXT:    jne LBB0_2
+; CHECK-NEXT:  ## %bb.1: ## %entry
+; CHECK-NEXT:    movsd {{[-0-9]+}}(%r{{[sb]}}p), %xmm0 ## 8-byte Reload
+; CHECK-NEXT:    ## xmm0 = mem[0],zero
+; CHECK-NEXT:    movsd %xmm0, (%rsp) ## 8-byte Spill
+; CHECK-NEXT:  LBB0_2: ## %entry
+; CHECK-NEXT:    movsd (%rsp), %xmm0 ## 8-byte Reload
+; CHECK-NEXT:    ## xmm0 = mem[0],zero
+; CHECK-NEXT:    movsd {{.*#+}} xmm1 = mem[0],zero
+; CHECK-NEXT:    addsd %xmm1, %xmm0
+; CHECK-NEXT:    movsd {{[-0-9]+}}(%r{{[sb]}}p), %xmm1 ## 8-byte Reload
+; CHECK-NEXT:    ## xmm1 = mem[0],zero
+; CHECK-NEXT:    ucomisd %xmm0, %xmm1
+; CHECK-NEXT:    setae %al
+; CHECK-NEXT:    movzbl %al, %ecx
+; CHECK-NEXT:    movl %ecx, %edx
+; CHECK-NEXT:    leaq {{.*}}(%rip), %rsi
+; CHECK-NEXT:    movsd {{.*#+}} xmm0 = mem[0],zero
+; CHECK-NEXT:    cvttsd2si %xmm0, %eax
+; CHECK-NEXT:    addq $40, %rsp
+; CHECK-NEXT:    retq
+entry:
+  %call = call i32 (...) @b()
+  %conv = sitofp i32 %call to double
+  %cmp = fcmp ole double fsub (double sitofp (i32 select (i1 icmp ne (i8* (i64, i64)* bitcast (i8* getelementptr (i8, i8* bitcast (i8* (i64, i64)* @calloc to i8*), i64 1) to i8* (i64, i64)*), i8* (i64, i64)* null), i32 1, i32 0) to double), double 1.000000e+02), %conv
+  %cond = select i1 %cmp, double 1.000000e+00, double 3.140000e+00
+  %conv2 = fptosi double %cond to i32
+  ret i32 %conv2
+}
+
+declare i8* @calloc(i64, i64)
+
+declare i32 @b(...)