[TargetLowering] expandFP_TO_UINT - avoid FPE due to out of range conversion (PR17686)

PR17686 demonstrates that for some targets FP exceptions can fire in cases where the FP_TO_UINT is expanded using a FP_TO_SINT instruction.

The existing code converts both the inrange and outofrange cases using FP_TO_SINT and then selects the result, this patch changes this for 'strict' cases to pre-select the FP_TO_SINT input and the offset adjustment.

The X87 cases don't need the strict flag but generates much nicer code with it....

Differential Revision: https://reviews.llvm.org/D53794

llvm-svn: 348251

1 files changed, 32 insertions, 56 deletions

diff --git a/llvm/test/CodeGen/X86/fp-cvt.ll b/llvm/test/CodeGen/X86/fp-cvt.ll
index 7a4d303163a..ab3d40ddcaa 100644
--- a/llvm/test/CodeGen/X86/fp-cvt.ll
+++ b/llvm/test/CodeGen/X86/fp-cvt.ll
@@ -483,29 +483,20 @@ define i64 @fptoui_i64_fp80(x86_fp80 %a0) nounwind {
 ; X64-X87-NEXT:    flds {{.*}}(%rip)
 ; X64-X87-NEXT:    fld %st(1)
 ; X64-X87-NEXT:    fsub %st(1)
+; X64-X87-NEXT:    xorl %eax, %eax
+; X64-X87-NEXT:    fxch %st(1)
+; X64-X87-NEXT:    fucompi %st(2)
+; X64-X87-NEXT:    fcmovnbe %st(1), %st(0)
+; X64-X87-NEXT:    fstp %st(1)
 ; X64-X87-NEXT:    fnstcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %eax
-; X64-X87-NEXT:    movw $3199, -{{[0-9]+}}(%rsp) # imm = 0xC7F
-; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movw %ax, -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fistpll -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fnstcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %eax
+; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %ecx
 ; X64-X87-NEXT:    movw $3199, -{{[0-9]+}}(%rsp) # imm = 0xC7F
 ; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movw %ax, -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fld %st(1)
+; X64-X87-NEXT:    movw %cx, -{{[0-9]+}}(%rsp)
 ; X64-X87-NEXT:    fistpll -{{[0-9]+}}(%rsp)
 ; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fucompi %st(1)
-; X64-X87-NEXT:    fstp %st(0)
-; X64-X87-NEXT:    jbe .LBB10_1
-; X64-X87-NEXT:  # %bb.2:
-; X64-X87-NEXT:    movq -{{[0-9]+}}(%rsp), %rax
-; X64-X87-NEXT:    retq
-; X64-X87-NEXT:  .LBB10_1:
-; X64-X87-NEXT:    movabsq $-9223372036854775808, %rax # imm = 0x8000000000000000
+; X64-X87-NEXT:    setbe %al
+; X64-X87-NEXT:    shlq $63, %rax
 ; X64-X87-NEXT:    xorq -{{[0-9]+}}(%rsp), %rax
 ; X64-X87-NEXT:    retq
 ;
@@ -515,17 +506,14 @@ define i64 @fptoui_i64_fp80(x86_fp80 %a0) nounwind {
 ; X64-SSSE3-NEXT:    flds {{.*}}(%rip)
 ; X64-SSSE3-NEXT:    fld %st(1)
 ; X64-SSSE3-NEXT:    fsub %st(1)
+; X64-SSSE3-NEXT:    xorl %eax, %eax
+; X64-SSSE3-NEXT:    fxch %st(1)
+; X64-SSSE3-NEXT:    fucompi %st(2)
+; X64-SSSE3-NEXT:    fcmovnbe %st(1), %st(0)
+; X64-SSSE3-NEXT:    fstp %st(1)
 ; X64-SSSE3-NEXT:    fisttpll -{{[0-9]+}}(%rsp)
-; X64-SSSE3-NEXT:    fld %st(1)
-; X64-SSSE3-NEXT:    fisttpll -{{[0-9]+}}(%rsp)
-; X64-SSSE3-NEXT:    fucompi %st(1)
-; X64-SSSE3-NEXT:    fstp %st(0)
-; X64-SSSE3-NEXT:    jbe .LBB10_1
-; X64-SSSE3-NEXT:  # %bb.2:
-; X64-SSSE3-NEXT:    movq -{{[0-9]+}}(%rsp), %rax
-; X64-SSSE3-NEXT:    retq
-; X64-SSSE3-NEXT:  .LBB10_1:
-; X64-SSSE3-NEXT:    movabsq $-9223372036854775808, %rax # imm = 0x8000000000000000
+; X64-SSSE3-NEXT:    setbe %al
+; X64-SSSE3-NEXT:    shlq $63, %rax
 ; X64-SSSE3-NEXT:    xorq -{{[0-9]+}}(%rsp), %rax
 ; X64-SSSE3-NEXT:    retq
   %1 = fptoui x86_fp80 %a0 to i64
@@ -577,29 +565,20 @@ define i64 @fptoui_i64_fp80_ld(x86_fp80 *%a0) nounwind {
 ; X64-X87-NEXT:    flds {{.*}}(%rip)
 ; X64-X87-NEXT:    fld %st(1)
 ; X64-X87-NEXT:    fsub %st(1)
+; X64-X87-NEXT:    xorl %eax, %eax
+; X64-X87-NEXT:    fxch %st(1)
+; X64-X87-NEXT:    fucompi %st(2)
+; X64-X87-NEXT:    fcmovnbe %st(1), %st(0)
+; X64-X87-NEXT:    fstp %st(1)
 ; X64-X87-NEXT:    fnstcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %eax
-; X64-X87-NEXT:    movw $3199, -{{[0-9]+}}(%rsp) # imm = 0xC7F
-; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movw %ax, -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fistpll -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fnstcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %eax
+; X64-X87-NEXT:    movzwl -{{[0-9]+}}(%rsp), %ecx
 ; X64-X87-NEXT:    movw $3199, -{{[0-9]+}}(%rsp) # imm = 0xC7F
 ; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    movw %ax, -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fld %st(1)
+; X64-X87-NEXT:    movw %cx, -{{[0-9]+}}(%rsp)
 ; X64-X87-NEXT:    fistpll -{{[0-9]+}}(%rsp)
 ; X64-X87-NEXT:    fldcw -{{[0-9]+}}(%rsp)
-; X64-X87-NEXT:    fucompi %st(1)
-; X64-X87-NEXT:    fstp %st(0)
-; X64-X87-NEXT:    jbe .LBB11_1
-; X64-X87-NEXT:  # %bb.2:
-; X64-X87-NEXT:    movq -{{[0-9]+}}(%rsp), %rax
-; X64-X87-NEXT:    retq
-; X64-X87-NEXT:  .LBB11_1:
-; X64-X87-NEXT:    movabsq $-9223372036854775808, %rax # imm = 0x8000000000000000
+; X64-X87-NEXT:    setbe %al
+; X64-X87-NEXT:    shlq $63, %rax
 ; X64-X87-NEXT:    xorq -{{[0-9]+}}(%rsp), %rax
 ; X64-X87-NEXT:    retq
 ;
@@ -609,17 +588,14 @@ define i64 @fptoui_i64_fp80_ld(x86_fp80 *%a0) nounwind {
 ; X64-SSSE3-NEXT:    flds {{.*}}(%rip)
 ; X64-SSSE3-NEXT:    fld %st(1)
 ; X64-SSSE3-NEXT:    fsub %st(1)
+; X64-SSSE3-NEXT:    xorl %eax, %eax
+; X64-SSSE3-NEXT:    fxch %st(1)
+; X64-SSSE3-NEXT:    fucompi %st(2)
+; X64-SSSE3-NEXT:    fcmovnbe %st(1), %st(0)
+; X64-SSSE3-NEXT:    fstp %st(1)
 ; X64-SSSE3-NEXT:    fisttpll -{{[0-9]+}}(%rsp)
-; X64-SSSE3-NEXT:    fld %st(1)
-; X64-SSSE3-NEXT:    fisttpll -{{[0-9]+}}(%rsp)
-; X64-SSSE3-NEXT:    fucompi %st(1)
-; X64-SSSE3-NEXT:    fstp %st(0)
-; X64-SSSE3-NEXT:    jbe .LBB11_1
-; X64-SSSE3-NEXT:  # %bb.2:
-; X64-SSSE3-NEXT:    movq -{{[0-9]+}}(%rsp), %rax
-; X64-SSSE3-NEXT:    retq
-; X64-SSSE3-NEXT:  .LBB11_1:
-; X64-SSSE3-NEXT:    movabsq $-9223372036854775808, %rax # imm = 0x8000000000000000
+; X64-SSSE3-NEXT:    setbe %al
+; X64-SSSE3-NEXT:    shlq $63, %rax
 ; X64-SSSE3-NEXT:    xorq -{{[0-9]+}}(%rsp), %rax
 ; X64-SSSE3-NEXT:    retq
   %1 = load x86_fp80, x86_fp80 *%a0