AMDGPU] Assembler: better support for immediate literals in assembler.

Summary:
Prevously assembler parsed all literals as either 32-bit integers or 32-bit floating-point values. Because of this we couldn't support f64 literals.
E.g. in instruction "v_fract_f64 v[0:1], 0.5", literal 0.5 was encoded as 32-bit literal 0x3f000000, which is incorrect and will be interpreted as 3.0517578125E-5 instead of 0.5. Correct encoding is inline constant 240 (optimal) or 32-bit literal 0x3FE00000 at least.

With this change the way immediate literals are parsed is changed. All literals are always parsed as 64-bit values either integer or floating-point. Then we convert parsed literals to correct form based on information about type of operand parsed (was literal floating or binary) and type of expected instruction operands (is this f32/64 or b32/64 instruction).
Here are rules how we convert literals:
    - We parsed fp literal:
        - Instruction expects 64-bit operand:
            - If parsed literal is inlinable (e.g. v_fract_f64_e32 v[0:1], 0.5)
                - then we do nothing this literal
            - Else if literal is not-inlinable but instruction requires to inline it (e.g. this is e64 encoding, v_fract_f64_e64 v[0:1], 1.5)
                - report error
            - Else literal is not-inlinable but we can encode it as additional 32-bit literal constant
                - If instruction expect fp operand type (f64)
                    - Check if low 32 bits of literal are zeroes (e.g. v_fract_f64 v[0:1], 1.5)
                        - If so then do nothing
                    - Else (e.g. v_fract_f64 v[0:1], 3.1415)
                        - report warning that low 32 bits will be set to zeroes and precision will be lost
                        - set low 32 bits of literal to zeroes
                - Instruction expects integer operand type (e.g. s_mov_b64_e32 s[0:1], 1.5)
                    - report error as it is unclear how to encode this literal
        - Instruction expects 32-bit operand:
            - Convert parsed 64 bit fp literal to 32 bit fp. Allow lose of precision but not overflow or underflow
            - Is this literal inlinable and are we required to inline literal (e.g. v_trunc_f32_e64 v0, 0.5)
                - do nothing
                - Else report error
            - Do nothing. We can encode any other 32-bit fp literal (e.g. v_trunc_f32 v0, 10000000.0)
    - Parsed binary literal:
        - Is this literal inlinable (e.g. v_trunc_f32_e32 v0, 35)
            - do nothing
        - Else, are we required to inline this literal (e.g. v_trunc_f32_e64 v0, 35)
            - report error
        - Else, literal is not-inlinable and we are not required to inline it
            - Are high 32 bit of literal zeroes or same as sign bit (32 bit)
                - do nothing (e.g. v_trunc_f32 v0, 0xdeadbeef)
            - Else
                - report error (e.g. v_trunc_f32 v0, 0x123456789abcdef0)

For this change it is required that we know operand types of instruction (are they f32/64 or b32/64). I added several new register operands (they extend previous register operands) and set operand types to corresponding types:
'''
enum OperandType {
    OPERAND_REG_IMM32_INT,
    OPERAND_REG_IMM32_FP,
    OPERAND_REG_INLINE_C_INT,
    OPERAND_REG_INLINE_C_FP,
}
'''

This is not working yet:
    - Several tests are failing
    - Problems with predicate methods for inline immediates
    - LLVM generated assembler parts try to select e64 encoding before e32.
More changes are required for several AsmOperands.

Reviewers: vpykhtin, tstellarAMD

Subscribers: arsenm, kzhuravl, artem.tamazov

Differential Revision: https://reviews.llvm.org/D22922

llvm-svn: 281050

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
index 744d7fb89e2..1b8b8a07302 100644
--- a/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
+++ b/llvm/lib/Target/AMDGPU/Utils/AMDGPUBaseInfo.h
@@ -19,6 +19,8 @@ class FeatureBitset;
 class Function;
 class GlobalValue;
 class MCContext;
+class MCInstrDesc;
+class MCRegisterInfo;
 class MCSection;
 class MCSubtargetInfo;
 
@@ -80,6 +82,23 @@ bool isVI(const MCSubtargetInfo &STI);
 /// \p STI otherwise return \p Reg.
 unsigned getMCReg(unsigned Reg, const MCSubtargetInfo &STI);
 
+/// \brief Can this operand also contain immediate values?
+bool isSISrcOperand(const MCInstrDesc &Desc, unsigned OpNo);
+
+/// \brief Is this floating-point operand?
+bool isSISrcFPOperand(const MCInstrDesc &Desc, unsigned OpNo);
+
+/// \brief Does this opearnd support only inlinable literals?
+bool isSISrcInlinableOperand(const MCInstrDesc &Desc, unsigned OpNo);
+
+/// \brief Get size of register operand
+unsigned getRegOperandSize(const MCRegisterInfo *MRI, const MCInstrDesc &Desc,
+                           unsigned OpNo);
+
+/// \brief Is this literal inlinable
+bool isInlinableLiteral64(int64_t Literal, bool IsVI);
+bool isInlinableLiteral32(int32_t Literal, bool IsVI);
+
 } // end namespace AMDGPU
 } // end namespace llvm