[RISCV] Fix incorrect use of Zfa fli instruction for negative minimum value. (#70411)

isSmallestNormalized() only considers the magnitude, not the sign.

Author: topperc

llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp

@@ -251,7 +251,7 @@ int RISCVLoadFPImm::getLoadFPImm(APFloat FPImm) {
          "Unexpected semantics");
 
   // Handle the minimum normalized value which is different for each type.
-  if (FPImm.isSmallestNormalized())
+  if (FPImm.isSmallestNormalized() && !FPImm.isNegative())
     return 1;
 
   // Convert to single precision to use its lookup table.

llvm/test/CodeGen/RISCV/double-zfa.ll

@@ -156,7 +156,8 @@ define double @loadfpimm17() {
 define double @loadfpimm18() {
 ; CHECK-LABEL: loadfpimm18:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    fli.d fa0, min
+; CHECK-NEXT:    lui a0, %hi(.LCPI16_0)
+; CHECK-NEXT:    fld fa0, %lo(.LCPI16_0)(a0)
 ; CHECK-NEXT:    ret
   ret double 0x8010000000000000
 }

llvm/test/CodeGen/RISCV/float-zfa.ll

@@ -110,7 +110,8 @@ define float @loadfpimm12() {
 define float @loadfpimm13() {
 ; CHECK-LABEL: loadfpimm13:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    fli.s fa0, min
+; CHECK-NEXT:    lui a0, 526336
+; CHECK-NEXT:    fmv.w.x fa0, a0
 ; CHECK-NEXT:    ret
   ret float 0xb810000000000000
 }

llvm/test/CodeGen/RISCV/half-zfa-fli.ll

@@ -216,7 +216,8 @@ define half @loadfpimm14() {
 define half @loadfpimm15() {
 ; CHECK-LABEL: loadfpimm15:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    fli.h fa0, min
+; CHECK-NEXT:    lui a0, %hi(.LCPI14_0)
+; CHECK-NEXT:    flh fa0, %lo(.LCPI14_0)(a0)
 ; CHECK-NEXT:    ret
 ;
 ; ZFHMIN-LABEL: loadfpimm15: